N.H. Rev. Stat. Ann. § 535:16

If improvements are found a decree shall be made that the state or petitioner pay to the grantee the value thereof, or such part of the value as the court may deem equitable, or that the grantee pay to the state or petitioner the value of the land before the improvements were made, and upon such payment that the grantee have the title of the state or of the petitioner thereto.