I can't find the problem in this chunk of code for a player's EXP leader statistics?

Okay, I have been going at this code for hours on end now, tried everything I can think of for a fix and yet my problem still occurs. The code works perfectly fine for level 1 to level 2 but after level 2 it suddenly starts adding 1 level per click of a move instead of adding the 20 exp that a move is supposed to add. I know that the problem is happening in this chunk of code I just don't know where. Someone please help before I lose my mind!

This is the chunk of code:

function exp(Value)

    if Player.leaderstat.EXP.Value >= Player.leaderstat.MaxEXP.Value then
        Player.leaderstat.EXP.Value = 1 --Player.leaderstat.EXP.Value - Player.leaderstat.EXP.Value
            wait()
        Player.leaderstat.LastLevel.Value = Player.leaderstat.LastLevel.Value + 1
            wait()
        Player.leaderstat.Level.Value = Player.leaderstat.LastLevel.Value + 1
            wait()
        Player.leaderstat.MaxEXP.Value = 15*(Player.leaderstat.Level.Value*2)
        GUI2.Exp.Bar.Size = UDim2.new(Player.leaderstat.EXP.Value/Player.leaderstat.MaxEXP.Value, 0, 0.65, 0)

    elseif Player.leaderstat.EXP.Value < Player.leaderstat.MaxEXP.Value and Player.leaderstat.EXP.Value >= 1 then
        GUI2.Exp.Bar.Size = UDim2.new(Player.leaderstat.EXP.Value/Player.leaderstat.MaxEXP.Value, 0, 0.65, 0)

    elseif Player.leaderstat.EXP.Value < 1 then 
        Player.leaderstat.EXP.Value = 1
    end

    if Player.leaderstat.Level.Value >= 300 then
        GUI2.Exp.Bar.Size = UDim2.new(0.955, 0, 0.65, 0)
    end
end