Add a new stimulus to to your workout by incorporating some high intensity interval training into your week. High Intensity Interval Training or HIIT- short bursts of intense exercise followed by a short rest period, and repeat. You can vary intensity within a session and sessions are usually @20 minutes in length. If 20 minutes sounds too short, then you need to ramp up the intensity.
Examples can range from sprint/ jog combinations to various bodyweight and resistance exercises at 30 second bursts w/ 60 second rests. Variations are unlimited. Benefits include improved cardio vascular fitness, athletic performance, and fat loss.