>>Surely there must be a way to re-add the audio track and correspond with the matching video.<<
Although this feature *might* exist, I'm not aware of it. I don't work with video but there's nothing in the audio features that would link separate events that would remain intact if one of the events is deleted from the project and then saved. You could place some markers in the timeline or something similar that would give you a place to line up events but you still have to do this by hand, eyes and ears. If you think you might need to refer/revert to an older version of a project, I think the easiest way to do this is to simply give each version a new name (without copying source media). For example, each time I do even a minor tweak on a mix, I name it sequentially something like "mix 1a, 1b, 1c, etc, and of course document some notes on what I did.