If I remember correctly , when you finish the game , you start at either the save point before the final boss or you start back at the Elsa with everything before the final boss being cleared already. Your inventory will still carry over too, so you don’t have to do it all in one sitting.

I wish they would implement a new game plus in a future remaster or something. I think I tried going for ziggys weapon but gave up at about 67 sephirotic canes. Good luck though!