CheckBot has been updated to give you the ability to access your category limits. To do this, make sure you don't have any accounts and categories with the same code, then enter the same message to checkbot with your category code.
For example, I have a category set up for food with the code of "f". To get the limit for my food category, I would enter "lim f" and CheckBot will reply with my limit.
Remember, if you're using a cellphone, enter the message as "clearcheckbook:lim f" with the number as 265010.