S.D. Codified Laws § 34-20A-82

A person recommitted under § 34-20A-81 who has not been discharged before the end of the ninety-day period shall be automatically discharged at the expiration of that period unless the administrator, or an authorized designee of the facility to which the patient is committed prior to expiration of the period, obtains a court order on the grounds set forth in § 34-20A-70 for recommitment for a further period not to exceed ninety days.