632.504.  Subsequent petitions for release — approval or denial procedures. — Nothing in sections 632.480 to 632.513 shall prohibit a person from filing a petition for release pursuant to sections 632.480 to 632.513.  However, if a person has previously filed a petition for release without the director's approval and the court determined either upon review of the petition or following a hearing that the petitioner's petition was frivolous or that the petitioner's condition had not so changed that the person was safe to be at large, then the court shall deny the subsequent petition unless the petition contains facts upon which a court could find the condition of the petitioner had so changed that a hearing was warranted.  Upon receipt of a first or subsequent petition from committed persons without the director's approval, the court shall endeavor whenever possible to review the petition and determine if the petition is based upon frivolous grounds and if so shall deny the petition without a hearing.