Possible to Re-tighten Muscles Without Entire New Tummy Tuck?

Technically, as Dr Placik points out, the re-tightening of the fascia is not difficult and can be accomplished with or without an endoscope.
However, the results can be disappointing.
First, the fascia may actually be tight, so additional sutures literally rip through, not achieving the effect the patient had been hoping for.
The usual reason patients develop a bulge after having originally undergone a tummy tuck is weight gain. That means there is more fat inside the abdomen. A tummy tuck retightening does not remove any of that fat, so tightening of the fascia can be a very disappointing experience for the patient expecting the results of their first tummy tuck.
The best results of the "re-tightening" procedure are with patients who have lost weight (including those who have had a pregnancy after a tummy tuck), where the fascia is legitimately loose, not just bulging because of fat inside the abdomen.
For cases where the bulge or "beer belly" appearance is unsightly, weight loss is by far the best (and healthiest) option for the patient.

Thank you for your question regarding re-tightening abdominal muscles after a previous tummy tuck. While it’s possible to address muscle laxity without removing excess skin, in most cases, a full tummy tuck revision may be necessary. This is because re-tightening the abdominal muscles often involves the same approach as the initial tummy tuck, which includes making an incision to access and repair the rectus muscles (the "six-pack" muscles).

In some situations, a mini tummy tuck or muscle repair alone might be an option, but it depends on the extent of the muscle separation, any remaining skin laxity, and how much scar tissue is present from the previous surgery. It’s important to consult with an experienced board-certified plastic surgeon to determine the best approach for your specific needs and desired outcomes.

Sincerely,
Dr. Katzen

As the other doctors have indicated, this can be done with a C-section type of scar.
My question, given your history, is whether or not muscle tightening is what would correct your issues. You could have excess skin, excess fat, or some combination of the two...which will obviously change the approach to get you the desired results.