Sorry I missed your inquiry previously.  If you added the two bottles and then the system has not had waste water for about three weeks, then I would probably not add more Septic-Scrub at this time.  You might monitor the water levels in the field after it starts up again.  If they start to rise and hold water, then more Septic-Scrub would be advised.  Otherwise a preventative maintenance program might include one bottle in the fall, and then ono to two bottles a year.