How do I increase a stat every certain amount of levels?

I am trying to make it so every 10 levels the player's max stamina goes up by half.

Code:

--//Services
local ReplicatedStorage = game:GetService('ReplicatedStorage')
local ServerStorage = game:GetService('ServerStorage')
local ServerScriptService = game:GetService('ServerScriptService')
local DataStoreService = game:GetService('DataStoreService')
local Players = game:GetService('Players')

--//Variables
local Level = DataStoreService:GetDataStore('Level')
local EXP = DataStoreService:GetDataStore('EXP')
local AEXP = DataStoreService:GetDataStore('AEXP')
local SkillPoints = DataStoreService:GetDataStore('SkillPoints')
local Stamina = DataStoreService:GetDataStore('Stamina')
local MaxStamina = DataStoreService:GetDataStore('MaxStamina')

--//Coding
function SaveData(DataName, PlayerId, Value)
    DataStoreService:GetDataStore(DataName):SetAsync(PlayerId, Value)
end

game.Players.PlayerAdded:Connect(function(Player)
    local PlayerStats = Instance.new('Folder')
    PlayerStats.Name = 'PlayerStats'
    PlayerStats.Parent = Player
    local PlayerLevel = Instance.new('IntValue')
    PlayerLevel.Value = Level:GetAsync(tostring(Player.UserId)) or 1
    PlayerLevel.Name = 'PlayerLevel'
    PlayerLevel.Parent = Player:WaitForChild('PlayerStats')
    local PlayerEXP = Instance.new('NumberValue')
    PlayerEXP.Value = EXP:GetAsync(tostring(Player.UserId)) or 0
    PlayerEXP.Name = 'PlayerEXP'
    PlayerEXP.Parent = Player:WaitForChild('PlayerStats')
    local PlayerEXPN = Instance.new('IntValue')
    PlayerEXPN.Value = AEXP:GetAsync(tostring(Player.UserId)) or 100
    PlayerEXPN.Name = 'EXPNeeded'
    PlayerEXPN.Parent = Player:WaitForChild('PlayerStats')
    local PlayerSkillPoints = Instance.new('IntValue')
    PlayerSkillPoints.Value = SkillPoints:GetAsync(tostring(Player.UserId)) or 0
    PlayerSkillPoints.Name = 'PlayerSkillPoints'
    PlayerSkillPoints.Parent = Player:WaitForChild('PlayerStats')
    local PlayerStamina = Instance.new('IntValue')
    PlayerStamina.Value = Stamina:GetAsync(tostring(Player.UserId)) or 100
    PlayerStamina.Name = 'PlayerStamina'
    PlayerStamina.Parent = Player:WaitForChild('PlayerStats')
    local PlayerMaxStamina = Instance.new('IntValue')
    PlayerMaxStamina.Value = MaxStamina:GetAsync(tostring(Player.UserId)) or 100
    PlayerMaxStamina.Name = 'PlayerMaxStamina'
    PlayerMaxStamina.Parent = Player:WaitForChild('PlayerStats')
    PlayerEXP.Changed:Connect(function()
        if Player.PlayerStats:WaitForChild('PlayerEXP').Value >= Player.PlayerStats:WaitForChild('EXPNeeded').Value then
            if Player.PlayerStats:WaitForChild('PlayerLevel').Value == 1000 then return end
            PlayerLevel.Value = PlayerLevel.Value + 1
            PlayerEXPN.Value = PlayerEXPN.Value + (PlayerEXPN.Value / 10)
            PlayerEXP.Value = 0
            PlayerSkillPoints.Value = PlayerSkillPoints.Value + 2
            PlayerMaxStamina.Value = PlayerMaxStamina.Value + (PlayerMaxStamina.Value / 2)
            PlayerStamina.Value = PlayerMaxStamina.Value
            SaveData('Level', Player.UserId, PlayerLevel.Value)
            SaveData('EXP', Player.UserId, PlayerEXP.Value)
            SaveData('AEXP', Player.UserId, PlayerEXPN.Value)
            SaveData('SkillPoints', Player.UserId, PlayerSkillPoints.Value)
            SaveData('PlayerStamina', Player.UserId, PlayerStamina.Value)
            SaveData('MaxStamina', Player.UserId, PlayerMaxStamina.Value)
        else
            SaveData('Level', Player.UserId, PlayerLevel.Value)
            SaveData('EXP', Player.UserId, PlayerEXP.Value)
            SaveData('AEXP', Player.UserId, PlayerEXPN.Value)
            SaveData('SkillPoints', Player.UserId, PlayerSkillPoints.Value)
            SaveData('PlayerStamina', Player.UserId, PlayerStamina.Value)
            SaveData('MaxStamina', Player.UserId, PlayerMaxStamina.Value)
        end
        SaveData('Level', Player.UserId, PlayerLevel.Value)
        SaveData('EXP', Player.UserId, PlayerEXP.Value)
        SaveData('AEXP', Player.UserId, PlayerEXPN.Value)
        SaveData('SkillPoints', Player.UserId, PlayerSkillPoints.Value)
        SaveData('PlayerStamina', Player.UserId, PlayerStamina.Value)
        SaveData('MaxStamina', Player.UserId, PlayerMaxStamina.Value)
    end)
end)

game.Players.PlayerRemoving:Connect(function(Player)
    SaveData('Level', Player.UserId, Player.PlayerStats.PlayerLevel.Value)
    SaveData('EXP', Player.UserId, Player.PlayerStats.PlayerEXP.Value)
    SaveData('AEXP', Player.UserId, Player.PlayerStats.PlayerEXPN.Value)
    SaveData('SkillPoints', Player.UserId, Player.PlayerStats.PlayerSkillPoints.Value)
    SaveData('PlayerStamina', Player.UserId, Player.PlayerStats.PlayerStamina.Value)
    SaveData('MaxStamina', Player.UserId, Player.PlayerStats.PlayerMaxStamina.Value)
end)