Your dragon is about the same size as mine when I decided to feed him more...best thing to do is keep giving him crickets (1/2 inch to 3/4 inch, well fed crickets (ie feed them same greens you give your dragon and any store bought gutload (or make your own)). Feed him as many as he can eat in about 10-15 minutes or till he just won't eat any more. Leave a nice amount of greens so he can pig out on those later on if he gets hungry.
I am assuming he is under a year old, so I would feed him twice a day, morning and at 5pm or so (just make sure he has at least an hour to digest before lights out). Again feed both greens and as many crickets he wants.
You can also give him silkworms..they get along bigger than crickets but have much more nutrients than a cricket. I have been feeding mine silkworms for a week now and he loves them. He only eats 3-5 of them per meal but that's because they fill him up quick. He then eats all his greens too. He's really growing now to, up to 13 inches from 10 in about two weeks.