Player gets a random data wipe?

I have a Data script that holds the players levels, exp and money (and a lot more, stats etc..) and the saving worked perfectly fine. But I've had it twice now when the data randomly resets to the old values.

Here is my script:

local DataStore = game:GetService("DataStoreService")
local Data = DataStore:GetDataStore("ManageData")

local prefix = 'user_'

game.Players.PlayerAdded:Connect(function(Plr)

    local stats = Instance.new("Folder", Plr)
    stats.Name = "Data"

    --- Level System

    local Levels = Instance.new("IntValue", stats)
    Levels.Name = "Levels"

    local Exp = Instance.new("IntValue", stats)
    Exp.Name = "Exp"

    local ExpNeed = Instance.new("IntValue", stats)
    ExpNeed.Name = "ExpNeed"

    --- Money System
    local Zeni = Instance.new("IntValue", stats)
    Zeni.Name = "Zeni"

    --- Stats Text
    local HealthP = Instance.new("IntValue", stats)
    HealthP.Name = "HealthPoints"

    local MeleeP = Instance.new("IntValue", stats)
    MeleeP.Name = "MeleePoints"

    local SpeedP = Instance.new("IntValue", stats)
    SpeedP.Name = "SpeedPoints"

    local KiMaxP = Instance.new("IntValue", stats)
    KiMaxP.Name = "KiMaxPoints"

    --- Stats System
    local Points = Instance.new("IntValue", stats)
    Points.Name = "Points"

    local MaxHealth = Instance.new("IntValue", stats)
    MaxHealth.Name = "Health Max"

    local Melee = Instance.new("IntValue", stats)
    Melee.Name = "Melee Damage"

    local Speed = Instance.new("NumberValue", stats)
    Speed.Name = "Speed"

    local KiMax = Instance.new("IntValue", stats)
    KiMax.Name = "Ki Max"

    -- KI DAMAGE --

    local KiDamage = Instance.new("IntValue", stats)
    KiDamage.Name = "Ki Damage"

    -- KI CONTROL --

    local KiControl = Instance.new("IntValue", stats)
    KiControl.Name = "Ki Control"

    -- HEALING POWER  --

    local HPower = Instance.new("IntValue", stats)
    HPower.Name = "Healing Power"

    -- POWER LVLS --
    local powerLvl = Instance.new("IntValue", stats)
    powerLvl.Name = "PowerLevel"

    -- STAMINA --

    local Stam = Instance.new("IntValue", stats)
    Stam.Name = "Stamina"

    -- START VALUES --

    Levels.Value = 1
    Exp.Value = 0
    ExpNeed.Value = 100
    Zeni.Value = 200
    HealthP.Value = 1
    MeleeP.Value = 1
    SpeedP.Value = 1
    KiMaxP.Value = 1
    Points.Value = 0
    MaxHealth.Value = 100
    Melee.Value = 5
    Speed.Value = 16
    KiMax.Value = 100
    KiDamage.Value = 5
    KiControl.Value = 5
    HPower.Value = 5
    powerLvl.Value = 5
    Stam.Value = 100

    -- SET DATA --

    local plrData = Data:GetAsync(prefix .. tostring(Plr.UserId))

    if plrData then
        Levels.Value = plrData[1] or 1
        Exp.Value = plrData[2] or 0
        ExpNeed.Value = plrData[3] or 100
        Zeni.Value = plrData[4] or 200
        HealthP.Value = plrData[5] or 1
        MeleeP.Value = plrData[6] or 1
        SpeedP.Value = plrData[7] or 1
        KiMaxP.Value = plrData[8] or 1
        Points.Value = plrData[9] or 0
        MaxHealth.Value = plrData[10] or 100
        Melee.Value = plrData[11] or 5
        Speed.Value = plrData[12] or 16
        KiMax.Value = plrData[13] or 100
        KiDamage.Value = plrData[14] or 5
        KiControl.Value = plrData[15] or 5
        HPower.Value = plrData[16] or 5
        powerLvl.Value = plrData[17] or 5
        Stam.Value = plrData[18] or 100

    else

        Data:SetAsync(prefix .. tostring(Plr.UserId), {
            Plr.Data.Levels.Value,
            Plr.Data.Exp.Value,
            Plr.Data.ExpNeed.Value,
            Plr.Data.Zeni.Value,
            Plr.Data.HealthPoints.Value,
            Plr.Data.MeleePoints.Value,
            Plr.Data.SpeedPoints.Value,
            Plr.Data.KiMaxPoints.Value,
            Plr.Data.Points.Value,
            Plr.Data["Health Max"].Value,
            Plr.Data["Melee Damage"].Value,
            Plr.Data.Speed.Value,
            Plr.Data["Ki Max"].Value,
            Plr.Data["Ki Damage"].Value,
            Plr.Data["Ki Control"].Value,
            Plr.Data["Healing Power"].Value,
            Plr.Data.PowerLevel.Value,
            Plr.Data.Stamina.Value
        })  
    end

-- SAVE STATS ON LEAVING --

game.Players.PlayerRemoving:Connect(function(Plr)
    Data:SetAsync(prefix .. tostring(Plr.UserId), {
            Plr.Data.Levels.Value,
            Plr.Data.Exp.Value,
            Plr.Data.ExpNeed.Value,
            Plr.Data.Zeni.Value,
            Plr.Data.HealthPoints.Value,
            Plr.Data.MeleePoints.Value,
            Plr.Data.SpeedPoints.Value,
            Plr.Data.KiMaxPoints.Value,
            Plr.Data.Points.Value,
            Plr.Data["Health Max"].Value,
            Plr.Data["Melee Damage"].Value,
            Plr.Data.Speed.Value,
            Plr.Data["Ki Max"].Value,
            Plr.Data["Ki Damage"].Value,
            Plr.Data["Ki Control"].Value,
            Plr.Data["Healing Power"].Value,
            Plr.Data.PowerLevel.Value,
            Plr.Data.Stamina.Value
        })
end)

Is there anything wrong with the script? Please let me know.