Hi! We really underestimated how much people would want to play the game in a sitting (we have so many people asking just this!), and have some cool ideas on how to fix this. Right now the only way is to go in and manually make back ups of your save files. It always saves to the same place, so just reinstalling the game wont fix it.
We have cool ideas on how to add new game+ or the ability to make new farms/profiles but it would be for at least another update, NEXT UP RACES! If you want to keep super up to date why not jump in our discord? Were super friendly/active and love feedback!