Any person subject to an order for involuntary admission pursuant to RSA 171-B:12 may file in probate court a petition setting forth such person's name, the underlying circumstances and date of the prior order of the court ordering such person's involuntary admission, a request for discharge from involuntary admission, and the reasons for such request. The petition shall be accompanied by the certificate of a physician, psychiatrist, or psychologist with experience and training in developmental and intellectual disabilities stating that the person is no longer in need of involuntary admission and setting forth the facts upon which such opinion is based. Upon receipt of the petition and the certificate, the court shall conduct a hearing pursuant to RSA 171-B.