Life happens, and sometimes we don't do all the workouts we would like to do. I wouldn't double up workouts to make up for the ones you missed. Maybe do 15-20 minutes more cardio, or more intense lifting. Take an extra walk. Doubling up your workouts may wear you out, and the following ones won't be as effective.
Try to plan your workouts and routines around your life happenings. If you are a student, then studying and passing IS priority.
Do or don't do; there is no try (Yoda)