N.H. Rev. Stat. Ann. § 529:26

The sale and deed made in pursuance thereof shall be void if, within one year after the sale, the debtor shall pay or tender to the purchaser the purchase money, and all reasonable sums paid by him for taxes, insurance, repairs and the redemption of mortgages upon the estate, to protect and preserve the interest purchased by him, with interest thereon from the dates of payments respectively, less the rents and profits received, or which might have been received, by him and with which he is justly chargeable.