Need to burn more calories but don't have the extra time to workout? You can do it without increasing your time in the gym. Just make your workout more challenging!
Using a treadmill? Increase the incline by 1% per workout and see if that doesn't burn a few more calories for you!
Are you waking but don't feel challenged? Break into a jog for 30 seconds and then walk. As soon as you feel you can do it again, GO FOR IT! Next time you walk increase your running to 1 minute.
Making small increases in your weight training will yield great results too. Increase weight gradually every 2 weeks or so. Add 1 - 2 lbs each for those small muscle group exercises and 5 - 10 lbs for large muscle groups.