Cal Mag, or epsom salts would be a good addition. They are sources of magnesium, which assists the plant with photosynthesis, plainly speaking. Your leaves will become really nice and green, provided the nutrient balance and ph are correct.
You should also look into a few cheap sources of humic acids. They will energize the plant. I don't know the juju behind humic acid's effect on the plant. I know it's good sheee-it, though.
Lastly, the plant with need a P-K boost during the ripening. Every nute program out there has some kind of high phosphorous additive you use in the final weeks before flushing. If you want to go on the cheap and organic route, pickup some indonesian bat guano. For hydro nutes, Grotek monster bloom is great, a cheaoer alternative to General Hydroponic's version. Both have similar n-p-k ratios.
Let me google that for you