I understand all your said about deleting and then adding the share, but with the exception of the following. How do I migrate the data up one level? Should I do this on the filer side or on the Window side?
> If you want to move the share and have it look the same, you'll need to migrate the data up one level, then change the shares.
How you move the data depends on the data, the tools you have available, and your downtime limitations. Easiest way would be to add the new share, disable the old share (downtime, so the data doesn't change), and do a host side copy. If you can't have that much downtime, use a tool like rsync or robocopy that lets you copy the data live, then only requires a short amount of downtime for a final sync and cutover.
Can't use snapmirror because you're in the same volume. You could use ndmpcopy, which will probably be a bit better than a windows side copy, but still requires downtime.