Your body will adapt to certain stresses certainly but it will not be necessary to complete stop the current program. One of the simplest ways of going about this is to substitute 1-2 new exercises every 3 weeks, be sure to progress across the exercise speed continuum where as you master a movement at one speed you can then graduate to faster speeds so long as you can maintain good form. Vary your rest periods and re-order the exercises will also work.
Using this combination of strategies will be sure to keep your body adapting, the workouts stimulating and ensure that you keep setting new limits
The website has a good selection of exercises that are not part of the all body express program and we will continue to talk about and post different exercises in the upcoming weeks