This is what I do for back-ups just to give you an idea:
Whenever I create a league, once it's ready to go I make a copy of the "lg" folder and tuck it away in a couple of places.
Then, every year I make a copy on 1 Jan, ST, Opening Day, AS Break, day after Championship. I just overwrite the previous copy each time once I'm satisfied all is good in my little fictional baseball world.
The original save never gets overwritten of course.