If, before the date set for hearing, application is made to the court of appeals for leave to present additional evidence on the issues in the case, and it is shown to the satisfaction of the court that the additional evidence is material and that there were good reasons for failure to present it in the proceeding before the agency, the court may order that the additional evidence be taken before the agency upon such conditions as the court deems proper. The agency may modify its findings and decision by reason of the additional evidence and shall file with the reviewing court, to become a part of the record, the additional evidence, together with any modifications or new findings or decision.