How can I update this gui every time the number increases?

local tool = script.Parent
Energy = 0

local player = game.Players.LocalPlayer

tool.Equipped:connect(function(mouse)
    local screenGui = Instance.new("ScreenGui")
screenGui.Parent = player.PlayerGui
local textLabel = Instance.new("TextLabel")
textLabel.Parent = screenGui
textLabel.Position = UDim2.new(0, 25, 0, 50)
textLabel.Size = UDim2.new(0, 150, 0, 50)
textLabel.BackgroundColor3 = BrickColor.White().Color
textLabel.Text = player.Name.."  Sah dude"..Energy


tool.Unequipped:connect(function(mouse)
    screenGui.Parent = nil
end)

end)


local tool = script.Parent
local keys = {}
tool.Equipped:connect(function(mouse)
    mouse.KeyDown:connect(function(key) keys[key] = true end)
    mouse.KeyUp  :connect(function(key) keys[key] = nil  end)
end)
while wait(0.2) do
    if keys["f"] then
        print "Charging"
        Energy = Energy + 5
    elseif keys["z"] and keys["x"] and Energy > 49 then
        print "Lol Idkek"
        wait(.5)
        Energy = Energy -50
    end
end

Whenever I hold down the F key, my energy increases by +5 every .2 seconds, but i would have to uneqeuip and then re-equip the tool in order for the number to change. Please help, cheers.