To explain further what Ice is saying, here is how to rollback to a given backup file:
First, you need to locate your saved files.
Mines are in Program Files (x86)\Steam\userdata\31706488\219740\remote... but if you go in your steam folder, you can search for
Survival_1 is your game in the first game slot, Survival_2 second slot and so on..
saveindex is where the game validates the Survival files when you try to load your game.
So, what needs to be done is to backup both saveindex and survival files. You can do it everyday.. once in a while.. whenever you want to be able to rollback to this point.
Whenever you die, you need to restore both files again. Be careful to backup all your files if you play multiple games at the same time.
Hope this helps!