N.H. Rev. Stat. § 464-A:11-a
A guardian or petitioner may seek an extension of a guardianship appointment by formally petitioning the court for a guardianship of the person and estate, the person, or estate within the period of any existing guardianship. Upon the filing of a petition for guardianship, a petition for an additional term of guardianship, a petition for an indefinite term of guardianship, or a petition for an amendment of the order or letters of guardianship to extend the term of the guardianship, the period of guardianship shall be extended until the issuance of the order of the probate court; provided that the probate court shall act upon the petition within 30 days of orders of notice being issued.
RSA 464-A:11-a
1995, 212:2. 2005, 90:1, eff. Aug. 6, 2005.