I was able to make a timer counting down thanks to previous forum discussions. However, for my game idea, I want to reward the player when they pass a level by giving extra time each time. So basically, whenever they pass a level, extra time is added to the remaining time they had in the previous level.

HA! I've got an answer! It's here!
You can drag the cat to the door; look at the variables.

To use this in your project, open the bar on the bottom left, and drag the cat to the bar. PLEEASE credit me if you use this! You might need to change the door block

<touching [door v] ?>

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Want to collab on this thingy? I can help.

I'd do this, to put your script with the time limit set and decreasing under a broadcast receiver; and everytime the player suceeds solving a level and start a new one broadcast to reset the time limit counter. Every level would be treated like an individual challenge, that way if the player fails solving a level they does not need to repeat the previous solved levels.