Repair of Mature Scar That Re-opened After 19 Years?

It is very, concernning that your wound has reopened. there are many many things that could cause this to happen. It is not normal.
You will want to obtain consultations from your general surgeon and a plastic surgeon to see your best option.

Hi there-
Without examining you, it is not possible to say with certainty what you might be dealing with or its appropriate management, but there is no question that what you describe is not normal.
You should see a surgeon right away.

I agree with Dr. Moelleken's & Aldea's recommendations. This is not at all normal and requires a full evaluation and work up to determine the cause as well as the treatment

 I agree with others that a scar doesn't ordinarily reopen after 19 years.  Possibilities include a portion of the material of the lap band has eroded through, permanent suture material has eroded through, an infection or some sort of new trauma or a tumor of sorts.
It's hard to know without looking at it but I'd start with a biopsy.  It's possible that depending on how loose the skin is the surgeon may be able to remove the wound entirely and reclose the new wound.
If you are near the St. Louis area, I highly recommend seeing Dr. Christian Paletta at St. Louis University.  He's excellent and will take good care of you.

I agree with the other docs, but would add that this should be biopsied and this needs to be done soon. This is most likely a benign condition, but the possibility of skin cancer or other malignancies must be considered. You must see your doctor ASAP.