Umm... what do you mean by level 2?
The beginning limit of each section is controlled by the number of kills/finishing blows, for the character. And the second limit of each section is controlled by X (8?, 12?, 14?) number of times that you use the first Limit.
(I think.)
Except for level 4...that one is gotten with an item....and I think it only has one. But...I don't really remember.