Although photos would be necessary to provide an accurate answer, if you have a significant amount of sagging skin after a tummy tuck a revision will likely be needed. If youve lost weight after your tummy tuck this may also be an indicator that a revision may be necessary. Some laxity will always be present when you bend down otherwise you would not be able to stand up straight. Post some photos or have your plastic surgeon take a look at you for a more definitve answer.
All the best,