The director shall cause to be made periodic reexamination of the status of each person who is committed to the department and who has not been finally discharged from such commitment, which shall:
(1) Include a study of all pertinent circumstances of such person's personal and family situation and an evaluation of the progress made by such person since the previous study;
(2) Be made for the purpose of ascertaining all relevant facts necessary to determine whether existing decisions, orders, and dispositions with respect to such persons should be modified or continued in force; and
(3) Be conducted as frequently as the department deems necessary but in any event, at intervals not to exceed six months with respect to each such person.