App you can
1.) "clone" your microsd (via
odin, or any other img creation tool),
2.) write it to a new high capacity one.
3.) Then extend the emunand partition via Gparted or something.
I never did it tho...
Extreme way would be to:
a) backup saves with jksv
b) make new emunand via hekate
c) reinstall games n restore saves.