On my second time logging in to play (first play-through), on the quest to kill the skeleton king, I decided to also pick up the Act 1 exploration achievements, like
A Nice Place to Visit and
I discovered that I hadn't received credit for any of the sections of
A Nice Place to Visit, most of which I had clearly already passed through, but was forced to revisit.
Do these sub-sections of exploration achievements get wiped, if you haven't completed the full achievement, when the maps are regenerated on login?