General alternatives:
* Routine
* Schedule
* Program
* System
* Plan
* Regime (this is a close synonym, often used in a more formal context)
More specific alternatives:
* Diet (if referring to a specific eating plan)
* Workout (if referring to a specific exercise plan)
* Treatment (if referring to a medical plan)
* Therapy (if referring to a psychological or rehabilitative plan)
* Course (if referring to a series of actions or events)
Informal alternatives:
* Way of life
* Lifestyle
* Habits
The best alternative will depend on the specific situation and what you want to emphasize.