Can I get a revision tip plasty without removing my Gore-Tex/ePTFE implant? (Photos)

Yes, you can, but be cautious as with another surgery with implant inside the nose , you might have a higher chance of having postoperative infection. Be sure to choose an experienced surgeon and would be better to be under prophylactic antibiotic coverage postoperatively. Goodluck !

Yes it can be done without removing the implant.

Tip-plasty
Tip-plasty is a great procedure to address a bulbous tip only and leave the rest of the nose alone. It can be accomplished through an open or closed approach. The goal is to refine the tip and make it smaller and smoother.
In tips with strong cartilages but thin skin, all that is needed is removing some of the cartilage and softening the rest by gently crushing it (morselizing).
In tips with thick skin and lot of soft tissue or fat, the excess fat and soft tissue is removed along with removing some of the cartilage.
Click on the video link below.
Regards
Dr. J

Absolutely. A second procedure may have a slightly increased complication rate, such as infection of the implant, but in careful, experienced hands I think that risk is small.