Had to recap my bottles to fill the level up so I didn't have any explode on me. Now they have been sitting for 2 1/2 weeks. Opened one up and there is no carbonation.. is there a way to recarbonate your beer?
There are carbonation drops that work on individual bottles. But this can be time consuming. I'd do as Brandon suggests and repitch. He's absolutely right about adding more sugar (DON'T). If you know of someone with a kegging system, there are bottling guns that work extremely well. These are pricey but you get much more consistent gas volumes in the bottle. Another way to carbonate by the bottle is to use dry ice. A small piece the size of your little fingernail should do the trick for each bottle. Just be certain to wear gloves to avoid frostbite.
Depending on how healthy the yeast were at bottling, and the temperature that your beer has been at since you bottled, you might not see carbonation yet.
From personal experience, I bottled a batch of beer right before moving out of state, and during the move, I let the freshly-bottled beer get too chilly. At 3 weeks, that beer had only a slight carbonation, but after warming the bottles to 70°F for 3 more weeks, it came out fine. I chose to be patient because I didn't want to go to a lot of extra work and potentially jeopardize my beer.
If you started with healthy yeast, and added the proper amount of priming sugar, and have kept your bottles in the proper temperature range for the yeast, it should take around 3 weeks to fully carbonate.
If you see absolutely zero carbonation at 2.5 weeks - there's not even a hint of a hiss when you uncap a beer and rigorous pouring doesn't produce any fizz - then it's possible that your yeast have died or are otherwise unviable.
Should that be the case, I would recommend pouring all of the bottles back into a sanitized carboy or bucket, and repitch healthy yeast and then re-bottle. If you added the correct amount of priming sugar at initial bottling do not add more sugar, as it could create overcarbonated beer and bottle bombs.
Your question is tricky since you mentioned in a previous question that you opened all your bottles. If those bottles hissed at all when you opened them, then the problem may not be the yeast, but that you've released some of your carbonation. Hopefully that's not the case, because then you'd need to evaluate how much more priming sugar to add. If that had happened, though, your beer would still be mostly carbonated, which it sounds like it is not.
And FWIW, if you underfilled your bottles the first time, you were at no risk of bottle bombs. The increased airspace would have been like an extra "cushion" that would cause undercarbonated beer.
I know this is a frustrating problem to work with, but be patient - it'll be worth the effort in the end.