I think you leave them be. Think about it - if you uncap the beer, add another drop, then re-cap, what have you done in step one? Release CO2. How much? Who knows? Do you then add TWO new carb drops? Probably not - that would be too much.
The good news is that it is usually easier to get a lot of flavor from a beer that is somewhat flat. As long as you have some carbonation, you may find that you like it with less carbonation.