Not that I am aware of (thats what I thought at first too) - I have gone from 2gb -> 4gb - 8gb -> 16gb, and now 32gb all the same way.
What I have always done is made an exact copy of my card and put it on my PC's hard drive as a backup. Before I upgrade, I always make sure I have the latest version of my card on my PC's drive, then I use a card reader (NOT the phone) and transfer the files to the new card that way, as it is way faster IMHO to do it that way.
It works for me!