Section 355.1. New hearing; staying, modifying or terminating an order

1.
  Upon a showing of a substantial change of circumstances, the  court  may
  on its own motion or on motion of the respondent or his parent or person
  responsible for his care:
    (a) grant a new fact-finding or dispositional hearing; or
    (b)  stay  execution  of,  set  aside, modify, terminate or vacate any
  order issued in the course of a proceeding under this article.
    2. An order issued under section 353.3,  may,  upon  a  showing  of  a
  substantial  change of circumstances, be set aside, modified, vacated or
  terminated upon motion of the commissioner of  social  services  or  the
  division for youth with whom the respondent has been placed.
    3.  If  the court issues a new order of disposition under this section
  the date such order expires shall not be later than the expiration  date
  of the original order.