Will this tumescent fluid that has been left behind after 9 days dissolve or reabsorb on its own?

The tumescent fluid is resorbed and excreted in your urine.  There is some swelling at this point.  It will take one month to see any results.  The final results are apparent at 6 months. What you are describing however is a fluid collection, which will not resolve without being drained. Make an appointment to see the surgeon.

Your body will slowly heal and remove the excess fluid from swelling and the tumescent fluid. Drink fluids, walk, and gently massage the treated area. Please follow your surgeon's post operative instructions.

Seromas are a collection of fluid, usually plasma, lymph and liquefied fat cells that can accumulate after any procedure. They need to be drained, to allow the skin to "stick" back down. This is a simple office visit where a small needle is placed through a numb skin area to aspirate the fluid. A compression dressing/garment is then placed to help prevent a repeat seroma. Most seromas will drain for weeks, be patient and allow your surgeon to drain these as often as needed.  Any person can drain a seroma, even a nurse.Good Luck!