Any association formed under the provisions of this chapter may extend its term of existence at any time within the last year of its then existing term, as evidenced by its articles of incorporation, or any amended articles, by filing with the secretary of state articles of incorporation such as are required for formation of an association, under the provisions of this chapter, and containing the additional statement that such articles are filed for the purpose of extending the term of existence of said association for such additional term as may be specified, not exceeding the term of fifty years for each separate extension.
SDCL 40-25-6