You mention cholecystectomy and fundoplication. Were these laparoscopic procedures? Did the hernia appeare at the site of the umbilical trocar? If so it might be a bit different umbilical hernia.
Indeed umbilical hernias are not going away on their own except in young children.
On the other hand they usually do not cause harm either. If it does not hurt, you might just wait and watch.
Mihai Mavru MD