When the grounds for a new trial could not with reasonable diligence have been discovered before, but are discovered after the time when the verdict, report of referee, or decision was rendered or made, the application may be made by petition filed as in other cases, not later than after the discovery, on which notice shall be served and returned, and the defendant held to appear as in an original action. The facts stated in the petition shall be considered as denied without answer. The case shall be tried as other cases by ordinary proceedings, but no motion shall be filed more than one year after the final judgment was rendered.