I just wanted to add something to this thread that others might find useful. My family and I travelled back to Canada as my father passed away in July. In all of the commotion that was going on up there, my wife misplaced her AP documents. We contacted the USCIS and were told that the only way for my wife to get back in was to get a replacement (read "new") AP. We could send an expedite letter to Evelyn Upchurch, but it could take weeks or months.
We called the border crossing that we entered Canada/US at. (Buffalo/Fort Erie Peace Bridge). We had a copy of her AP. She also has stamps in her passport from using the AP earlier in the trip (like the week prior) to cross into the US. Plus myself and the kids all had our valid AP documents. But still, everybody refused to use their brain, as anyone could see that she did legitimately have an AP. (Plus they have computers, don't they... ;-) )
Needless to say, we were quite distraught. Somebody suggested that we call an airport border crossing just to give it one more try. We contacted the USCIS at Toronto Airport and the officer told my wife that with all of the documents mentioned above, she'd have about a 90% chance of getting through. We booked my wife a plane ticket and she went to the airport.
When she got there, she went to secondary inspection. She broke down crying and the officer was very comforting to her. He promised her that they were going to get her back home (to the US) and that they (meaning the USCIS) are not all monsters. In the end, she paid $65 and got a humanitarian parole which allowed her to reenter the US.
I hope this information will prove useful to someone. I know that when I searched, the only answer seemed to be, reapply and wait....Even the USCIS doesn't seem to know, or are unwilling to use, all of the options available.
Regards
Rav