How do I raise my prices without losing customers?

I have an established service/business I have been running for years, and I am considered an expert in my field. I am rebuilding our very old site, which will have many new features and a membership aspect. Unfortunately, my pricing has remained the same over the last several years, and I have always given away more for free than I should have from a business standpoint. I want to make this a viable business model and compensate myself for the time I pour into it. The new site launch brings so much to the table, but it will also cost more to maintain. How do I raise my prices without losing my customers? How do I price our new products without pricing them out? There is no one else who provides this local service.