In my experience, the majority of lips that look like they need to be lengthened really only need to be released from a tented position attached to the nose. What I mean is that the large nose pulls up on a normal upper lip, making it appear short.
An easy test is to look in the mirror and push the tip of the nose down, if the lip appears normal then the lip lenght is fine.
Another cause of the short lip look is excessive bone at the anterior nasal spine. If you push your finger up at the angle between the columella and the lip and feel a very prominent bone, this can be causing the lip look you do not like.
Finally, a short lip for most people is attractive - ususally it is teh other stuff that makes the lip look unattractive.