First of all, great job on sticking with your exercise program — it sounds like you’ve found something that really works for you. But if you’ve been doing the same exercises, in the same order, for nearly 9 months, it’s definitely time for a change.
For best results, change your workout routine every 4-6 weeks or so to prevent fitness plateaus and boredom. New exercises and routines stimulate your body to continue adapting — so you’ll keep getting stronger and more fit. Keep the circuit training format if you prefer, but swap out some of the exercises for new ones that target the same muscle groups. For example, instead of chest press, you could do push-ups; instead of leg press, you could do squats or lunges; and you could replace jumping jacks with some stair climbing. You could also do the exercises in a different order. Consider cross-training, which involves swapping out your normal workout for something entirely different — like a group fitness class, a swim, or a run — once or twice a week.
For strength exercises, increase your level of resistance by about 5% when you can perform the recommended number of repetitions and sets — generally 1-3 sets of 8-12 repetitions— using proper form in two consecutive workouts.