Is there any possible way of seconds being added to a length

Hello developers,

So i am currently trying to figure out on how to add seconds on a length that is ongoing.
Here is the line of code which starts the timer: (length = 360)

for i = length, 0, -1 do

I want to make it so it adds 30 seconds to the timer but im not really sure on how to do so.
I attempted to make it add to the timer and it worked but then after a second, it instantly put it back to its original time.
Here is my attempt at adding time:

i += 30

Any help would be highly appreciated!

Try using while loop.

local i = length
while i > 0 do
   i -= 1
   task.wait(1)
   print(i..' Second pased')
end
i += 30

Now with using your way

for i = length, 0, -1 do
   -- Your code
end
length += 30

Could you please provide any usecase or your full code of this problem so I can understand it more?