Mo. Rev. Stat. § 211.036
If a youth under the age of twenty-one is released from the custody of the children's division and after such release it appears that it would be in such youth's best interest to have his or her custody returned to the children's division, the juvenile officer, the children's division or the youth may petition the court to return custody of such youth to the division until the youth is twenty-one years of age.
(L. 1989 H.B. 502, et al., A.L. 2013 S.B. 205 merged with S.B. 208)