Rick,

One way to know is by the number of clients you are landing. Are you having any issues getting clients at your current price? If not, your prices may be set too low. This may sound counter-intuitive, but you want clients to question your pricing. This gives you a chance to justify your rates and fees.

The other way to know is by the quality of your clients. Are most of your clients easy to work with or are some of them nothing but headaches? Raising your prices will deter clients that want everything for a small fee. Getting rid of clients will also make you feel better (as you won't always be stressed about them reaching out for changes or revisions at the last minute). Also, if a client doesn't seem like a good fit, turn them down. Start saying "no" and you may actually see your profit margin go up.