Level Up is an equipable item that appears in Kingdom Hearts 358/2 Days and Kingdom Hearts Re:coded. It increases the user's level by one.. KHGuides presents a comprehensive guide to abilities in Kingdom Hearts Final Mix.
I don't have a chart readily available, but if you're looking to level to 100, starting at night will get you there fastest.. For Kingdom Hearts on the PlayStation 2, Statistics/Level-Up Bonus Guide by falconesque.