Humor can be a touchy thing because it can be very subjective. One person’s humorous anecdote can be another person’s offensive slur. At this point you know your ex’s sense of humor and she knows yours. Depending on the specifics, humor can be an asset or a liability to you. Assuming your ex thinks your attempts at humor are generally funny you can use it to break the ice when you attempt to contact her. Be careful though, because an over reliance on humor can be viewed as a crutch to cover shortcomings.
Your ex would know about your personality, but like Magic of Making Up argues, you should be on your best behavior, while still being you. Your ex will likely see through an attempt to reinvent yourself as a funny, happy go lucky guy if this is not your personality. Making someone laugh is a good thing and if you can make your ex laugh it is a tool you can use to get her back.