S.D. Codified Laws § 15-6-6
(b).Enlargement of time
When by this chapter or by a notice given thereunder or by an order of court an act is required or allowed to be done at or within a specified time, the court for cause shown may at any time in its discretion:
(1) With or without motion or notice order the period enlarged if request therefor is made before the expiration of the period originally prescribed or as extended by a previous order; or
(2) Upon motion made after the expiration of the specified period permit the act to be done where the failure to act was the result of excusable neglect
Source: SDC 1939 & Supp 1960, § 33.0108; SD RCP, Rule 6 (b), as adopted by Sup. Ct. Order March 29, 1966, effective July 1, 1966.