I thought it would be a nice add-on if you got new exploration XP when discovering an area that has been majorly changed by the DMs. It is after all a new discovery, even if in a familiar place.

I do not know how the system is technically made, but if it is easy to reset the area's exploration status after major change, I think it would be a nice add-on. For example when Frederick's Hall was turned back into Seeker Hall.

I generally did. After exploring many areas several months back and then taking a break, I found myself gaining XP in a few areas that had been drastically changed since then.