Mass Effect 2: New Game Plus

In ME1, the level cap for the first playthrough was 50, once you finished a playthrough it was bumped to 60 for all subsequent playthroughs.

ME2 doesn't increase the level cap, once you hit 30 you're done.

The level cap is fixed at 30 for all playthroughs in ME2. From the ME2 wiki:

The new level cap is 30. Further advancing powers no longer is a simple point per power advancement system. Powers now cost an increasing number of points to advance and offer a specialization choice when maxed out. Since you can only max out five powers, this greatly affects play style of the characters. As such it is now possible to reset your advancement and reset your character in-game. However, your main character can gain new powers throughout the game, and unique powers can be unlocked for team mates through game play.

As was in Mass Effect, all party members gain experience and level up simultaneously regardless of their participation in missions or if/when they are recruited. Each time the party levels up, Shepard is awarded two additional squad points to spend on skill development. Other party members receive two squad points at each new level from levels 1 to 5 and two points every two levels from level 5 to 19. After level 19 party members receive only one squad point every two levels.