Well at this point he's confirmed too many times that there will be new levels and new dialogues (he said "new characters" once). I expect a new chapter in the castle (or a few new stages added to ch VI and VII, but that would make little sense considering how he pushes the idea of playing "past" the ending).
I'm excited about the new skills and new monsters bit. If this is anything close to the quality of Undead Nightmare I'll be willing to dish 15€ for that.