How do I add more "variety" to my wardrobe?

Hey everyone,

I've been getting into fashion pretty heavily for the past year and a half. I almost exclusively shop at J Crew and J Crew Factory, as I like their colorful button-downs and their slim fit. As a result, my closet is about 70% J Crew button downs (mix of patterned and plain), with a couple plain long sleeve t-shirts, two pairs of jeans, and a variety of different colored shorts. Not much day to day variety-- so what would you suggest that I purchase, and where else would you suggest that I shop, so that I can add variety to my wardrobe but maintain a preppy look?