How do you justify a price increase?
Customers understand that market realities change, but no one likes a hike in price that isn't justified. Consistently delivering on and increasing the value of your product or service, is a sure way to keep customers around. When customers are happy and dependent on your product, the more understanding they'll be with any pricing changes, and likely be willing to pay the extra money. You should, however, have solid research and/or quality improvements to back your pricing changes. Regular pricing updates also condition customers to expect changes.