Any corporation organized under the provisions of this subchapter may at any time within the two years next previous to the date of the expiration of its corporate existence, by a vote of the shareholders owning two-thirds of its stock, apply to the Board of Governors of the Federal Reserve System for its approval to extend the period of its corporate existence for a term of not more than twenty years, and upon certified approval of the Board of Governors of the Federal Reserve System such corporation shall have its corporate existence for such extended period unless sooner dissolved by the act of the shareholders owning two-thirds of its stock, or by an Act of Congress or unless its franchise becomes forfeited by some violation of law.