N.H. Rev. Stat. Ann. § 624:5

No offense committed and no penalty or forfeiture incurred, under any of the acts repealed by house bill no. 75 of the 1955 session of the general court, and before the time when such repeal shall take effect, shall be affected by the repeal, except that when any punishment, penalty, or forfeiture shall be mitigated by the provisions of the Revised Statutes Annotated, such provisions may be extended and applied to any judgment to be pronounced after such repeal.