The first playthrough brings you from level 1 to 51. After you start NG+, the game starts over at level 51.
How far does this playthrough bring you? Will you get all the way to level 100 on the second playthrough, or does it stop somewhere and make way for a third playthrough with the same character with even more difficult foes?
How many repetitions of NG+ exist, and what are the appropriate level ranges for each?