Is a repeat hiata hernia serious?

Yes: Hiatal hernia in and of itself can be considered serious when it causes symptoms. Most commonly this is gastroesophageal reflux, which can lead to a more serious condition of esophageal cancer. If a hiatal hernia recurs, following a previous repair, then this requires a truly expert surgeon to repair. This surgeon is someone who other surgeons refer complex problems.

Could be: Most hiatal hernias don't even cause symptoms. Large ones are also referred to as paraesophageal hernias, and are usually also asymptomatic. They do however have a low risk of serious, life threatening complications. See a general or thoracic surgeon with experience in laparoscopic hiatal hernia repair for more info.