Increase the intensity of your workouts by taking less breaks and less rest periods.
Add cardio intervals in between sets to really maximize your time in the gym and maximize calories burnt.
Add more compound movements to your workouts (exercises that require multiple muscles to be engaged such as: squats, lunges, pullups, jumps, etc.), it will burn more calories overall.
Make sure you’re eating a well-balanced diet for your body and your goals. Remember calories in versus calories out and that your diet effects your training. The better you eat, the better and more efficient your training will be.
Make sure you’re doing enough volume either by doing enough exercises in your workout or increasing reps and sets.