Hi Brian,
Just thought I would let you know what I found out from BUNAC on your/my fiance's situation. They've told me that people already on the WHP program CAN apply for a second visa (for another year), but that they cannot guarantee when those visas will come available. Last year it was around January-February. You have to go through the exact same rigmarole as previously, including all fees.
WHP visas process quickly (I recall having Tom's in hand within about three weeks), but the danger is that they might not even come available until the end of January, leaving you in a bit of a sticky wicket if yours expires. I understand as well though, that you can process the application by mailing to the London/Paris office, which means it can feasibly be done from inland (if we go this route, we'll forward all the materials to his mother and she will submit them), but it is necessary to go out of the country and back in again (i.e. you'd have to take another trip home when the visa is ready, so that it could be properly validated), which can get a little costly, especially if you were just there.
So ultimately, there is a way! You just might find there is a little extra expense/time involved. I'd get a request in with BUNAC right away if you chose to go this route, so that the process can be as quick as possible.
Good luck!