Plateaus can be broken by applying the FIT(M) principle: Frequency, Intensity, Time (duration) or Mode (type of workout). Take a look at your current routine and decide which of these variables makes the most sense to manipulate.
You already stated that you can't work out any longer, so how about adding an extra day of pure cardio? Cardiovasuclar activity is key in lowering bodyfat, and 4-5 times per week is recommended. You can shorten two of your cardio days (non-consecutive) to 30-40 minute sessions but make them more intense, the purpose being to burn more calories in less time. Too many days of longer sessions often leads to overuse injuries and burnout.
If you are doing the same type of cardio each workout, consider cross-training with a different activity to shock your muscles. If you strength train the same way every session, change it up. Increase the intensity, or change the order of the exercises, or substitue new exercises that challenge the same muscle group. Any time you give your muscles something new and different to do, it produces what is called a Training Effect, and the TE is key to breaking plateaus and pushing you forward toward your goals.
Every time your body plateaus, use the FIT(M) principle and choose a variable to manipulate, but don't get too over-zealous. Slow, steady progress is the goal.
Hope this is helpful! ;-)
-Roe