It's important to understand that when paying for something that is not a commodity, people don't pay for the perceived value. If your clients understand you give them great value and they trust you and have been working with you for a long time, they will pay the new price.
If prospects understand the value you give is greater than the price they will pay the price.
If you solve big problems you can have big price tag.
I suggest talk to your current and long time clients, be open about it, and tell them you'd like to get their impact on something. Ne real and genuine and see what their reaction is