How to tone lower belly portion?

I'm petite and is in shape. I've been working out. I work out 2-3 times a week. I attend kickboxing cl. My body is tone but my lower ab/or my lower belly section still has flubber. How do I get rid of it. I can't lose weight because I weigh 95 pounds and there is no way I can lose weight when i'm already skinny. How can and should i do to tone my lower belly. Thanks!