If you're not strength training, then now is the time to add some muscle to your frame. Strength training will boost your metabolism and help change your body composition to lose fat and gain muscle.
If you're already lifting, then you might need to make your strength training more intense. Bump up the frequency of your training from two to three times a week. Increase the amount of weight you're lifting to challenge your muscles even more or try a more challenging exercise. For example, skip the triceps kickback, which only works the back of the arms, and try triceps dips or side planks, since they work a variety of muscle groups. When you're pressed for time, remember that full-body exercises, like push-ups or burpees, give you more bang for your buck.
Try one of these circuit workouts. They will keep your heart rate up while strengthening your entire bod.