Why does it continue adding after the NumberValue reaches 1000?

So I have a NumberValue that is called Health and I want the max health to be 1000 and the min 0, if at any point it is under 1000 I want it to regenerate back to 1000 with a random interval of 1 to 50 but after 1000 it continues forever? Help! Here is what I had:

script.Parent.Value = 1000
while script.Parent.Value <= 1000 do
repeat 
script.Parent.Value = script.Parent.Value + math.random(1,50)
wait(math.random(1,5)) 	
until
script.Parent.Value == 1000
end

Because you are seeing if it equals 1000. Since you are doing math.random(1,50) there's a chance that it could pass 1000. To fix that do script.Parent.Value >= 1000

Also you don't need the repeat until in there.

You can just do this

script.Parent.Value = 1000 --Not sure what's this for
while script.Parent.Value <= 1000 do
script.Parent.Value = script.Parent.Value + math.random(1,50)
wait(math.random(1,5))  
end

script.Parent.Value = 1000 --This will set it to 1,000 afterwards if you want it too.

Never check if a number is exactly equal to something unless you know for certain that it will be. In this case, adding a random amount can very easily go over 1000 without reaching it.

The easiest way to make this work as expected is to connect the Changed event of the IntValue (I presume it is an Int and not a NumberValue) and have it set some 'regen' variable for use in an infinite loop:

local hp = script.Parent
local regen = false

hp.Changed:connect(function()
	regen = hp.Value < 1000
end)

while wait() do
	if regen then
		local healing = math.random(50)
		if healing > 1000 - hp.Value then --So we don't accidentally overheal.
			healing = 1000 - hp.Value
		end
		hp.Value = hp.Value + healing
		wait(math.random(5))
	end
end