I think you can reallocate the points to the AKV reservation you already have, UNLESS you made the AKV reservation more than 7-months away. If it was made more than 7-months out then you used home resort priority for the reservation, and cannot convert it over to SSR points.
If your original AKV reservation was made at 7-months or less prior to the scheduled checkout date, than I think you can just reallocate which points to use.
However there are a lot of special things concerning AKV reservations, including who was eligible to make reservations where and when, so some special issues may occur where your reservation is concerned.
Worse case would be you'd have to rebook pending availability.