Both of my boys also STILL have umbilical hernias. N's is a lot bigger than E's. They said we just need to wait it out and consider surgery if it hasn't improved by age 4 or so. They're 18 months.
btw - since it is clear there - anyone else deal with an umbilical hernia? It seems like the main thing you do is... nothing?
My niece had one. The doctor said that the only thing you can "kind of" do is make their diaper snug around their belly button (if you can get the diaper that high) to sort of keep it popped in. That's practically impossible, and really doesn't fix it.
Hers resolved itself within 18 months or so. I think my sister was also told to sort of "pop it back in" gently when she was changing her. Slowly over time, the opening in the muscle became smaller, allowing less to come through, then one day, it was closed and she was all "sealed up".
In some instances I think that if a surgical fix is needed, it's pretty simple. Maybe one of the easiest types of childhood hernies to repair.
I have an umbilical hernia. I never knew until I had a ct scan done a few years ago. My doctor said I've probably had it since birth and as long as it doesn't bother me, they won't do anything.