Tapered cigars (perfectos, torpedos, pyramids, salomoes, etc) are quite popular, and, in my opinion, should be cut slightly differently from round vitolas.
First and foremost, you need to use a quality cutter. I am partial to the Palio, but also own and use Xicar. Both feature very sharp blades that do not dull quickly and carry a warranty.
For your perfecto, I recommend cutting off approximately 1/2″ at an angle not to exceed 30 degrees. The angle opens up more surface for your draw and will gum up less than a straight cut.
I also do not recommend re-clipping. If your cigar does begin to gum up at the tip, re-clipping might be your only option (and, in my opinion, means that you did not clip enough initially). The main problem I see with re-clipping is the potential damage to the wrapper leaf. Even with a high-quality cutter, the wrapper is now moister than when you first cut it, which can cause an uneven clip and even a tear.
Many of my favorite cigars are tapered at the end, and I am very pleased with the results of clipping at an angle.