The answer to your question is yes you can add another coat or two. Lighlty sand it first so it has something to really adhere to.

On another note, permagloss will give a super finish but you have to do a few things to obtain that, unless you apply it super thin and many coats. I spin the rod on a rod drying motor at 43 rpm while applying and leave it turning for about 15 minutes after application so that it doesn't have the opportunity to "sag". Most folks don't have that capability to do that so what you would need to do is to apply very thin and even coats, and after the first two or thee coats applied, begin applying light coats with the brush tip running perpendicular to the wraps, rather than around the wraps.

This stuff isn't like applying epoxy where you can manually turn it by hand every 5 minutes or so until it begins to set up. As you know, it goes on nice and easy and is pretty thin so it will have a tendency to run. It does however set up very quickly and that is a plus.