So I finaly completed the game and i'm wondering if there are any new things I can do in NG+ that I couldn't do? th eonly think I know is that I can carry over pretty much everything from my previous playthrough and get to select the difficulty, is that all or are there new places to explore?

As a reward for climbing the Gate of Guidance a second time, you finally get to invade Heaven and layeth the rapeth down on all those angels' bitchasses!

Okay, that's a lie, but it shouldn't be. You'll get Aly and Flan as 2 unique units relatively early, and if you didn't already have Liz and Maki from importing a BB1 save you'll get that too. That's it. All of the other unique units like Mr. Tofu are unlocked from reinvestment instead of NG+.