How I can save my XP and LVL in this script ? [closed]

local Properties = Game.Workspace.GAME_PROPERTIES

function onXPChanged(player, XP, level) 
    if string.lower(Properties.XPType.Value) == "linear" then --Linear (1, 2, 3, 4, 5, etc)(High level cap recommended.)
        if XP.Value>= Properties.XPPerLevel.Value * (level.Value) + Properties.AdditionalXPNeeded.Value and level.Value < Properties.LevelCap.Value then 
            XP.Value = XP.Value - (Properties.XPPerLevel.Value*(level.Value) + Properties.AdditionalXPNeeded.Value) 
            level.Value = level.Value + 1 
        end 
    elseif string.lower(Properties.XPType.Value) == "square" then --Square (1, 4, 9, 16, 25, etc)(Medium level cap recommended.)
        if XP.Value>= Properties.XPPerLevel.Value * (level.Value * level.Value) + Properties.AdditionalXPNeeded.Value and level.Value < Properties.LevelCap.Value then 
            XP.Value = XP.Value - (Properties.XPPerLevel.Value * (level.Value * level.Value) + Properties.AdditionalXPNeeded.Value)
            level.Value = level.Value + 1 
        end
    elseif string.lower(Properties.XPType.Value) == "exponent" then --Exponent (1, 2, 4, 8, 16, etc)(Low level cap recommended. Exponent rate dictated by XPPerLevel divided by 100.)
        if XP.Value>= math.pow(Properties.XPExponentMagnitude.Value/100, level.Value-1) * Properties.XPPerLevel.Value + Properties.AdditionalXPNeeded.Value and level.Value < Properties.LevelCap.Value then 
            XP.Value = XP.Value - math.pow(Properties.XPExponentMagnitude.Value/100, level.Value-1) * Properties.XPPerLevel.Value + Properties.AdditionalXPNeeded.Value
            level.Value = level.Value + 1 
        end         
    end
end 

function onLevelUp(player, XP, level) 
    if player.Character~=nil then 
        for i = 1,5 do 
            local fireworks = Instance.new("Part") 
            fireworks.Shape = 0 
            fireworks.formFactor = "Symmetric" 
            fireworks.Size = Vector3.new(1,1,1) 
            fireworks.BrickColor = BrickColor.Random() 
            fireworks.CFrame = player.Character.Head.CFrame + Vector3.new(0,2,0) 
            fireworks.Parent = game.Workspace 
            game:GetService("Debris"):AddItem(fireworks, 2) 
            fireworks.Velocity = Vector3.new(math.random(-30,30),math.random(-30,30),math.random(-30,30)) 
        end 
    end 
    local m = Instance.new("Hint") 
    m.Parent = game.Workspace 
    m.Text = player.Name .. " has gained a level!" 
    wait(5) 
    m.Parent = nil 
end 

function SaveData(Player)
    if Player.DataReady == false then
        warn("Could not save, DataReady is false.")
        return
    end
    --Stats
    local Stats = Player.leaderstats:GetChildren()
    for i = 1, #Stats do
        if Stats[i]:IsA("IntValue") or Stats[i]:IsA("NumberValue") then
            Player:SaveNumber(Stats[i].Name, Stats[i].Value)
        elseif Stats[i]:IsA("BoolValue") then
            Player:SaveBoolean(Stats[i].Name, Stats[i].Value)
        elseif Stats[i]:IsA("StringValue") then
            Player:SaveString(Stats[i].Name, Stats[i].Value)
        end
    end
    --Attributes
    local Attributes = Player.attributes:GetChildren()
    for i = 1, #Attributes do
        Player:SaveNumber(Attributes[i].Name, Attributes[i].Value)
    end
    --Armors
    local Armors = Player.UnlockedArmor:GetChildren()
    for i = 1, #Armors do
        if Armors[i]:IsA("IntValue") or Armors[i]:IsA("NumberValue") then
            Player:SaveNumber(Armors[i].Name, Armors[i].Value)
        elseif Armors[i]:IsA("BoolValue") then
            Player:SaveBoolean(Armors[i].Name, Armors[i].Value)
        elseif Armors[i]:IsA("StringValue") then
            Player:SaveString(Armors[i].Name, Armors[i].Value)
        end
    end
    print("Data has been saved successfully for " .. Player.Name .. "!")
end

function LoadData(Player)
    if Player.DataReady == false then
        warn("Could not load, DataReady is false.")
        return
    end
    --Stats
    local Stats = Player.leaderstats:GetChildren()
    for i = 1, #Stats do
        if Stats[i]:IsA("IntValue") or Stats[i]:IsA("NumberValue") then
            local temp = Player:LoadNumber(Stats[i].Name)
            if temp >= 0 then --Prevents the loading of negative stats.
                Stats[i].Value = temp
            end
        elseif Stats[i]:IsA("BoolValue") then
            local temp = Player:LoadBoolean(Stats[i].Name)
            Stats[i].Value = temp
        elseif Stats[i]:IsA("StringValue") then
            local temp = Player:LoadString(Stats[i].Name)
            Stats[i].Value = temp
        end
    end
    --Attributes
    local Attributes = Player.attributes:GetChildren()
    for i = 1, #Attributes do
        local temp = Player:LoadNumber(Attributes[i].Name)
        if temp >= 0 then
            Attributes[i].Value = temp
        end
    end
    --Armors
    local Armors = Player.UnlockedArmor:GetChildren()
    for i = 1, #Armors do
        if Armors[i]:IsA("IntValue") or Armors[i]:IsA("NumberValue") then
            local temp = Player:LoadNumber(Armors[i].Name)
            if temp >= 0 then
                Armors[i].Value = temp
            end
        elseif Armors[i]:IsA("BoolValue") then
            local temp = Player:LoadBoolean(Armors[i].Name)
            Armors[i].Value = temp
        elseif Armors[i]:IsA("StringValue") then
            local temp = Player:LoadString(Armors[i].Name)
            Armors[i].Value = temp
        end
    end
end

function onPlayerEntered(newPlayer)

        --Variables folders
        local stats = Instance.new("Model")
        stats.Name = "leaderstats"

        local attrb = Instance.new("Model")
        attrb.Name = "attributes"

        local misc = Instance.new("Model")
        misc.Name = "Stats"

        local armor = Instance.new("Model")
        armor.Name = "UnlockedArmor"

        --Leaderstats variables
        local clicks = Instance.new("IntValue", stats)
        clicks.Name = "Lvl"
        clicks.Value = 1

        local clicks2 = Instance.new("IntValue", stats)
        clicks2.Name = "XP"
        clicks2.Value = 0

        local clicks3 = Instance.new("IntValue", stats)
        clicks3.Name = "Gold"
        clicks3.Value = 0

        --Attributes
        local attrb1 = Instance.new("IntValue", attrb)
        attrb1.Name = "Strength"
        attrb1.Value = Properties.StartingAttributes.Value

        local attrb2 = Instance.new("IntValue", attrb)
        attrb2.Name = "Constitution"
        attrb2.Value = Properties.StartingAttributes.Value

        local attrb3 = Instance.new("IntValue", attrb)
        attrb3.Name = "Intelligence"
        attrb3.Value = Properties.StartingAttributes.Value

        local attrb4 = Instance.new("IntValue", attrb)
        attrb4.Name = "Dexterity"
        attrb4.Value = Properties.StartingAttributes.Value

        --Other stats
        local mana = Instance.new("IntValue", misc)
        mana.Name = "Mana"
        mana.Value = 100

        local maxmana = Instance.new("IntValue", misc)
        maxmana.Name = "MaxMana"
        maxmana.Value = 100

        local equippedArmor = Instance.new("StringValue", misc)
        equippedArmor.Name = "EquippedArmor"
        equippedArmor.Value = "None"

        local defense = Instance.new("IntValue", misc)
        defense.Name = "Defense"
        defense.Value = 0

        --Unlocked armors
        local unlockedArmorLeather = Instance.new("BoolValue", armor)
        unlockedArmorLeather.Name = "UnlockedLeather"
        unlockedArmorLeather.Value = false

        local unlockedArmorChainmail = Instance.new("BoolValue", armor)
        unlockedArmorChainmail.Name = "UnlockedChainmail"
        unlockedArmorChainmail.Value = false

        local unlockedArmorBronze = Instance.new("BoolValue", armor)
        unlockedArmorBronze.Name = "UnlockedBronze"
        unlockedArmorBronze.Value = false

        local unlockedArmorIron = Instance.new("BoolValue", armor)
        unlockedArmorIron.Name = "UnlockedIron"
        unlockedArmorIron.Value = false

        local unlockedArmorSteel = Instance.new("BoolValue", armor)
        unlockedArmorSteel.Name = "UnlockedSteel"
        unlockedArmorSteel.Value = false

        local unlockedArmorMithril = Instance.new("BoolValue", armor)
        unlockedArmorMithril.Name = "UnlockedMithril"
        unlockedArmorMithril.Value = false

        local unlockedArmorAdamant = Instance.new("BoolValue", armor)
        unlockedArmorAdamant.Name = "UnlockedAdamant"
        unlockedArmorAdamant.Value = false

        local unlockedArmorDemonic = Instance.new("BoolValue", armor)
        unlockedArmorDemonic.Name = "UnlockedDemonic"
        unlockedArmorDemonic.Value = false

        local unlockedArmorBone = Instance.new("BoolValue", armor)
        unlockedArmorBone.Name = "UnlockedBone"
        unlockedArmorBone.Value = false

        --PvP       
        if Properties.HasPvP.Value == true then
            local clicksPvP = Instance.new("IntValue", stats)
            clicksPvP.Name = "PvP Points"
            clicksPvP.Value = 0

            local inPvP = Instance.new("BoolValue", misc)
            inPvP.Name = "InPvP"
            inPvP.Value = game.Workspace.GAME_PROPERTIES.GlobalPvP.Value
        end

        --Assign the folders to player.
        stats.Parent = newPlayer
        attrb.Parent = newPlayer
        misc.Parent = newPlayer
        armor.Parent = newPlayer

        clicks2.Changed:connect(function() onXPChanged(newPlayer, clicks2, clicks) end) 
        clicks.Changed:connect(function() onLevelUp(newPlayer, clicks2, clicks) end) 

        newPlayer:WaitForDataReady(true) 

        LoadData(newPlayer)

        newPlayer.CharacterAdded:connect(function(c) 
            c.Humanoid.MaxHealth = (Game.Workspace.GAME_PROPERTIES.StartingHP.Value) + (Game.Workspace.GAME_PROPERTIES.HPPerLevel.Value * newPlayer.leaderstats.Lvl.Value) + (Game.Workspace.GAME_PROPERTIES.HPPerConstitution.Value * newPlayer.attributes.Constitution.Value)
            c.Humanoid.Health = c.Humanoid.MaxHealth
        end) 
end 

function onPlayerRemoving(player)
    print("Attempting to save score for " .. player.Name)
    SaveData(player)
end

game.Players.PlayerAdded:connect(onPlayerEntered)
game.Players.PlayerRemoving:connect(onPlayerRemoving)