I under-primed: can I prime again?

Was brewing a one-gallon extract batch and stupidly used two teaspoons of priming sugar instead of two tablespoons. Dissolved in water, poured into secondary carboy for mixing and then bottling.

Bottles are already capped. So my question: can I uncap them, add more primer, and re-cap? I mean, I know I can, but is it a good idea? I still have lots of the little pellets that come with NB kits. Or should I be worried about this at all, even?

Looks like you may get about 2vols of carbonation which is a bit low for an American style ale but it will carbonate. Call if a British ale which are less carbonated. With luck you may have bottled if before it was completely fermented out which will give you a little more. It’s only a1gallon batch so I would leave it alone for now. Keep it at 70 deg for 2 weeks and then chill it to drink. If you still think it’s under carbonated you could uncap and drop a 1/2 sugar cube in and recap.