If at the hearing it should appear that any person entitled to notice has not been served with notice, the board may postpone such hearing and fix a new time for the same, and notice of such new time of hearing may be served on such omitted persons in the manner and for the time provided by law and by fixing such new time for hearing and by adjournment to such time, the board shall not lose jurisdiction of the subject matter of such proceeding nor of any persons previously served with notice.
Iowa Code § 468.603
89 Acts, ch 126, §2