Reversing CAW changes.

I open my world in CAW and then used it to "Edit In Game". I was adding rooftop features to my Science Centre (telescopes, greenhouse, chess tables, solar panels, windmills). I then switched to a different lot that needed some corrections and noticed that a lot of things had changed. It took me a while to figure out what happened, but I think Origin dropped my expansion packs again after I shut down last night. This hasn't happened to me in CAW before. I saved my changes after the Science Centre edits. Now I'd have to redo my entire world if I can't undo that save(s). What do I do?