Hmm, how old is your ReptiSun bulb? If more than 6-8 months get a new one. Independent testing shows that the UV output drops off after about 6 months. The Repti Aid vitamin/calcium may not be the greatest. Generally calcium/mineral and vitamin powders need to be kept separate rather than combined...they breakdown faster if mixed. Check to be SURE what vitamins are included in yours. Mineral or calcium dusts may say they have vitamins included, but may only contain Vit. D3 to help with calcium uptake. If D3 is all the dust contains he's not getting other vitamins such as A, the B complex etc. Better yet, use a good gutload instead of the off the shelf brands. You can very easily make a better gutload than buy one. There are great recipes for gutloads on this site:
http://www.adcham.com
And, about the best commercial gutload out there is available from:
http://www.herpnutrition.com
Get him outdoors in direct sun if the weather permits such as an hour or two every weekend (when you are around to watch...or get a portable cage such as a Reptarium so you don't lose him). His appetite will slowly decrease as he gets older too, as he's not growing as fast. See if this helps!