What is wrong with my Exp Bar script?

I've made this Exp Bar script to display the Experience of the player out of how much they need to level up. It sets the size originally, when the game begins, but when I change my experience nothing happens.

Code:

wait(2)

local xps = {0, 3, 6, 10, 15, 20, 25, 30, 40, 50,
    65, 80, 95, 110, 125, 140, 155, 180, 210,
    250, 300, 350, 400, 450, 500, 575, 650, 725,
    825, 1000};

function hudsize()
    local Player = game.Players.LocalPlayer
    repeat wait() until Player and Player.leaderstats
    local ExpBar = script.Parent.ExpBar
    local xp = Player.Exp.Value
    local level = Player.leaderstats.Level.Value


        local required = ((xps[level] * 100)/xp)
        wait(.1)
        local size = (required * 200)
        wait(.1)
        ExpBar.Size = UDim2.new(0,15,0,size)

        end

while wait(.5) do
    hudsize()
end