Section 15. If execution is levied on rents and profits, the annual value thereof shall be determined by the appraisers, and the land shall be set off to the creditor for such time as will satisfy the execution at the rate of rents and profits as determined by the appraisers, if the life estate endures so long, computing interest on the amount due on the execution and deducting the rents and profits as they accrue as so much paid from time to time. If the life estate expires before the end of the term so fixed, the creditor may have a new action on the judgment to recover the amount then due thereon.