How do you make specific saving points in an obby?

I've been trying to find any way to make my obstacle course have a save where they are given the option when they rejoin the game after reaching a specific point and leaving if they wanted to continue off from that specific point. What I mean by that, I plan on making a permanent checkpoint in my obstacle course every 13 rounds so they would've have stay hours to finish the entire thing. So when they rejoin, they would be given an option off of a GUI whether they wanted to respawn from that particular area. The only problem though, I tried looking high and low from free models and the forum but I couldn't find anything that was adequate to my situation. I was wondering how exactly I'm supposed to do this so people don't have to restart my obstacle course if they don't want to.