It’s seems pretty clear, between the Live Trigger system (where you can generally only choose one dialogue option), other mutually-exclusive choices, and the talk of monthly DLC that Square-Enix expects people to play through Final Fantasy XIII-2 multiple times.
But it’s not clear, at least to me, whether there’s a new game plus option, where you can keep some or all of your original progress as you restart the game: an interview (in Japanese) back in December 2011 supposedly mentioned the mode, but neither the manual nor the official strategy guide mention it, and I can’t find a confirmation from anyone who actually played the game that the mode was ever implemented.
Is it available, or is it impossible to get 100% completion in any individual play-through due to various decision trees locking certain options out?
It’s kind of irrelevant as you can bounce around between each time period and zone whenever you’d like. From New Game+ for FF XIII-2:
There isn’t really a new game+.
You’re just able to reverse time so you can replay any section of the
story or area once you find a reverse clock item [seal] in the corresponding