Wis. Stat. § 24.29: Redemption.

At any time before the 5 days next preceding the reoffering at public sale of any land forfeited under s. 24.28, the former purchaser, or the former purchaser’s assigns or legal representatives, may prevent the resale of the forfeited lands and revive the original contract by paying the principal sum due, with interest, and all taxes returned on the forfeited lands to the secretary of administration that are still unpaid, and all costs occasioned by the delay, together with 3 percent damages on the whole sum owing for the forfeited lands.