Yes there is a bit left before the battle tower. After you are done Maxos temple you can head to sentinel island. Your first encounter there you can mindread to bring you up a level, so you may want to put off going until you finish everything else you can and just reach a level, to get the maximum effect from that. I went to the fjords and got to level 18 before going to sentinel island, though you certainly don't need to do so.
