How often should I raise my prices?
At least annually, and whenever your costs rise. Certainly if the cost of labor, garments, inks and other supplies and/or rent rises, you should factor that increase into your new prices. If you don't, you're just putting everything on sale, but your customers won't even know it.
Even if costs stay pretty consistent, I recommend a small price increase every six to 12 months. A 1 percent price increase is likely to go unnoticed by most customers. Since costs will rise sometime in the future, you can buffer this for your customers by increasing them in consistent, small increments.