How can I burn more fat?

I've been on a tough workout regimen since January. I workout 5-6 days a week, and twice a day 4 days out of that week. Tue. through Friday I workout by doing cardio in the a.m. usually about 30-45 min. and then p90x after work, yet I can't seem to shed enough body fat. My goal was to drop from 250lbs to 200lbs, but I've been stuck at 225lbs for the past 3 months, and I've been working out regularly since January. My cloths fit looser, but I want to reach my goal of 200lbs. How can I burn more body fat?