The gloss white should gloss itself up all by itself. If it's not, you can try like wingnut said, car wax and a buffer.
Otherwise I'd say strip it back down and start over, making sure you prime it really well. In order to coax a shine out of something, you can take a wet 1000 or 1500 sandpaper and lightly sand down between layers. This will make the next layer pop much better. Prime, sand, prime sand, paint, sand, paint sand, paint, clear coat. Should do it.