The KB gives a good example of what to do (mirror, rename old to new, new to old) and you have to destroy and recreate the vfiler. There is no other way intra-filer to do this. The KB gives a qtree snapmirror (QSM) example but in most cases you'll use volume snapmirror (VSM) since it is a best practice to assign a full volume to a vfiler instead of individual qtrees.
Here is another workaround... vfiler migrate or vfiler data motion the entire vfiler from this controller to another controller, then vfiler migrate or vfiler data motion it back. When you migrate back, create the volumes in any aggrs you want. Brute force but prevents you from having to destroy and recreate the vfiler...but does require you migrate the vfiler and all volumes out and back...but we have done this for similar reasons and it works well.