Chap. 8, section A (If the applicant is classified as a drug abuser or addict, the applicant can apply again for an immigration benefit if his or her drug abuse or addiction is in remission. Remission is now defined by DSM criteria, and no longer by a set timeframe as it was under previous Technical Instructions. In order for an applicants drug abuse or addiction to be classified as in remission, the applicant must return to a civil surgeon for a new assessment.) (emphasis added).
http://www.uscis.gov/policymanual/HTML/PolicyManual-Volume8-PartB-Chapte...