Depending on how your umbilical hernia was repaired, it is possible that the circulation to your belly button has been compromised. Your body will re-establish some of that circulation over time but it is unpredictable. There is always a small theoretical risk of losing your belly button with a tummy tuck, although it is very uncommon. In your situation that risk is now increased because of your previous hernia repair. Your plastic surgeon is being cautious and wants you to fully understand all the risks.
It is difficult to "create" a new belly button and it really never looks completely normal and it wouldn't be any better than if a new button was created afterwards. There are some adjustments that your surgeon could make to minimize the risk of loss of your belly button but your only other alternative would be to not have the tummy tuck surgery.
It sounds to me like your surgeon is being cautious which is very good thing! We plastic surgeons think about bllod supply all the time because so many of our operations by their very nature compromise blood supply.
If you were my patient, I would likely go ahead with the tummy tuck and assess the umbilicus for circulation. If it looked like a goner, a new one could be reconstructed at the time of the tummy tuck.
Although I need to see the reports and examine you, in general I do not agree with the assessment. The umbilical blood supply is hardy. It is difficult to knock off that blood supply. In nearly 20 years of practice and thousands of abdominoplasties, some complex ones dealing with patients with massive weight loss, I have never come across compromise of the umbilicus. As my colleagues have eluded, the umbilical hernia can also safely be repaired during a tummy tuck. The fact that you have had yours repaired and now are going for a tummy tuck is actually the safest and most logical approach. Make sure you are seeing a qualified plastic surgeon who is certified by the American Board of Plastic Surgery and make sure that they have wide experience with abdominoplasty.
and have one reconstructed 4-6 months post-op. Besides being better in many cases, it makes your tummy tuck safer. I routinely reconstruct belly buttons when the original one is not pretty or compromised as yours is. This also avoids the circumferential scar and often really round belly button that result from tummy tucks.
Tummy tuck surgery and umbilical hernia repair can be accomplished safely at the same procedure, assuming a particular hernia repair technique is employed. Staged repair if umbilical hernia and tummy tuck surgery can also be safe, but this depends on a variety of technique and timing factors.