My intermission timer automatically stops ticking, how can I fix this?

I'm making an intermission for my round-based game. So, like any intermission, I have a timer GUI. It's supposed to tick down for 15 seconds and when it gets to 0, it will teleport all players to the map.

The problem is, the TextLabel which I set the text to display the intermission timer's value will automatically stop ticking at 14. Can someone help? Here's my code:

repstorage = game.ReplicatedStorage
timer = game.StarterGui.RoundTimer.TimerText

local intermission = Instance.new("IntValue")
	intermission.Name = "Intermission"
	intermission.Value = 15
	intermission.Parent = game.ReplicatedStorage
	
function countdown()
	repeat
		intermission.Value = intermission.Value - 1
		timer.Text = intermission.Value
			wait(1)
	until intermission.Value == 0
	
	if intermission.Value == 0 then
		intermission.Value = intermission.Value + 15
	end
end

repstorage.ChildAdded:Connect(countdown)

go easy on me

Maybe try this, I have an intermission script and it works fine.

local timer = game.StarterGui.RoundTimer.TimerText

function intermission()
for i = 15,0,-1 do
timer.Text = ""..i..""
wait(1)
end)
while true do
intermission()
wait(1)
end

This should work. But it doesn't do it every time a player joins. Good Luck!