N.H. Rev. Stat. Ann. § 552:7

Any party interested may have the probate of a will which has been proved without notice re-examined, and the will proved in solemn form before the court of probate at any time within 6 months of such probate. Any issue related to the execution of a will, testamentary capacity, or fraud, duress, or undue influence shall be tried to the court of probate, and any party interested may request the same within 6 months of such probate.