Skin elasticity and round 2 BBL. Will my skin be able to stretch so that I can have more volume? (Photo)

Skin elasticity can certainly affect the amount of fat that can be injected.  Realize that about 50% of the fat will survive from the first BBL.  Having the BBL done a second time is an option as long as the patient has enough fat to be transferred.  The percentage of fat survival in the BBL the second time should be about the same as the first.   The volume loss occurs over the first 6 weeks or so.  After that period of time, the volume remains stable assuming weight is maintained.  
Kenneth Hughes, MD, ABPS Board Certified Plastic Surgeon
Los Angeles, CA

I can not see your results from your photos so it is hard to say.  If you have enough donor sites, then it is possible to add more.

You are an excellent candidate for a Brazilian Butt Lift (BBL) revision. The optimal BBL outcomes are achieved with: 1) use of VASER liposuction to harvest the fat, 2) a closed looped system such as Puregraft to process the fat, and 3) strategic micro-packet transplant technique. These three processes have demonstrated over 95% fat graft take. This means that your results will be stable as long as you maintain your weight. As an official VASER trainer, I am routinely referred unhappy BBL patients. One of the most common reasons for disgruntled BBL patients is that patients are not able to accurately communicate their desired buttocks goals to their surgeons.  A buttocks assessment tool ban be an invaluable tool to communicate to your surgeon the exact buttocks size and shape you are desiring. A Skype or Facetime consultation with a BBL specialist can help you get an accurate recommendation and pricing.
Respectfully,
Arian Mowlavi MD, FACS
Realself 100 Hall of Fame Inductee