After you defeat the game you unlock the New Game+ feature. When playing in New Game+ mode, the items, Oculi, and Confessions that you earned through the first play-through will be carried to the next new game. This also includes all your levels and skills once the characters can be re-recruited.Your enemies will be stronger, but you won't be, and you won't have your coffers either!
Unlock Plus Mode (New Game +)
First you must finish and clear the game once to unlock "New Game+" mode. Then, you start New Game+. You will start the game with all of the Oculi, Confessions, and Items (except for Quests) that you had are carried over, as are your characters' levels and skills (once you progress far enough in the story to recruit them again). All of the Coffers that you collected are reset and will need to be found again. Finally, enemies have been scaled up in strength and EXP.