Questions level

You have a few options, but the main two I would recommend would be to:
-A) just play the game until you reach the desired level
-B) use something like iWeb to edit your characters exp to a value like 2147473648 {something where it (X) plus the amount of EXP you'll get from the next mob WILL NOT exceed 2147483648} -- then log in and kill a mob. If doing it once does not obtain the desired level you'll have to rinse lather and repeat, until you do reach the desired level.

However (as I've already said), you CAN NOT use a number that when added to the gain from a mob you kill that will equal higher than 2147483648. example. Lets say you made your characters EXP 2147483646, if you then killed a mob that would yield you 1 exp, you'd be fine because 2147483646+1=2147483647 (still under 2147483648). Conversely if you used 2147483646, but then killed a mob that would yield 100 exp, you would actually screw up your character because 2147483646+100=2147483746 && 2147483746>2147483648... So the main point is the number you use + next mob kill EXP reward HAS to be < 2147483648 [This is why I say 2147473648 is a pretty safe number to use, it gives you a leeway of 10000]