How can I get this foor loop to work?

How can I get this to work?

local MoveUntil = 20
local Text = game.Workspace.Text

while true do
	if game.Players.NumPlayers > 0 then
		Text.Value = "The game is ready"
		wait(2)
		Text.Value = "The battle will begin in: "
		for i = 10, 1, -1 do
			wait(1)
		end
		Text.Value = "All fighters to the doors"
		wait(2)
		Text.Value = "The doors are now opening"
		wait(1)
		Text.Value = ""

		repeat 
    		for k, r in pairs(game.Workspace.InvisibleWalls:GetChildren()) do 
        		r.CFrame = r.CFrame+ Vector3.new(0,1,0)
    		end
    		wait(0.1)
		until game.Workspace.InvisibleWalls:GetChildren()[1].Position.Y >= MoveUntil

	else
 		Text.Value = "You need 2 players to begin"	
	end
	wait(1)
end

How can I get this to continously float up by 1 block?