I see no reason why you wouldn't be able to feed it, assuming the soil doesn't have ferts added, such as miracle gro. I don't know how peppers respond to fertilizers, so maybe do a half strength feeding and see what that gets you.
Are you growing outdoors, indoors? Soil, soil less? If outdoors...in ground, containers?
I second this, my peppers prefer Low nitrogen. I use Foxfarm with Tap Water. My tap water is about 280ppm, and at FULL SIZE my peppers like around 900-1000ppm and 5.9 to 6.4PH. I usually feed my small peppers around 500ppm of week bloom solution with tap water included, if they can handle more after a week, increase the strength of the solution by 50-100ppm.. This means that I use about 220ppm of nutrient solution on my small peppers.