Scar Revision or Tummy Tuck to Remove Vertical Scar?

It appears you have an irregular vertical scar from the picture. The underlying muscle may also be loose causing a midline separation or diastasis.
The excess skin below the belly button or umbilicus could be removed through the vertical scar, improve the appearance of the scar, and at the same time tighten the underlying muscle. An additional horizontal scar may allow more skin to be removed. Liposuction could also be performed to remove any unwanted fat deposits.
Consult a board certified plastic surgeon to discuss these options to achieve the best result in rejuvenating the lower abdomen.

There will definitely be a tradeoff between having a horizontal scar and having the vertical scar if you opt for a full tummy tuck. This option would "clean up" the area around the belly button, but the horizontal scar would likely be rather high given that you don't seem to have much extra skin.
The choice will ultimately be yours once you know the pluses and minuses.