Unfortunately there is nothing you can do to guarantee you won't get the dreaded plantar fasciitis again.  The same biomechanics (or the way your foot works) that got you into the problem will still be present and can rear their ugly head again.  However, having suffered through a case of plantar fasciitis myself, I can give you some good tips that help keep the pain away.  

  1. Wear the insoles or orthotics you were prescribed.  I wear custom orthotics and love them! Can't do a run without them. 
  2. Continue to stretch, even if only for a few minutes a day.  I do it while my kids are brushing their teeth!
  3. Keep your night splint handy. After a full day of walking, being on your feet, or after a long run be sure to still wear it. 

If your pain should recur, get back into the routine that was originally prescribed by your doctor.  If your pain doesn't resolve in a week or two its time to come back in and see your doctor.