The party to whom a new trial is granted shall, prior to such new trial, pay the costs of the former trial, unless the court enter that the new trial is granted for misconduct of the opposite party, who, in such case, may be ordered to pay any costs which seem to the court reasonable. Such costs shall include the allowances to witnesses as provided in § 17.1-612. If the party who is to pay the costs of the former trial fails to pay the same at or before the next term after the new trial is granted, the court may, on the motion of the opposite party, set aside the order granting it, and proceed to judgment on the verdict or award execution for the costs, whichever seems best.