I use one or more of the methods below, depending on the complexity of the model:
Save a new version at regular time intervals so I can go back in "history" and retrieve an earlier version of the object(s). You can open two instances of MoI and copy/paste objects between them.
Copy an object before performing fillets and booleans and move it off to the side for safe keeping.
Copy an object before performing fillets and booleans, assign a unique Style (color), then hide it. Easy to bring it back at any time and it will be in the same position.