You have only "lost" these customers if they have gone somewhere else to have framing done. And I'm sure we all lose customers from time to time, but I think a far greater issue is the fact that they are not having anything framed at all! In other words, they are just not "repeating."
As Dave said, the whole idea is to make sure that they always think of you when they need your services. We do that by staying "visible."
Most businesses think that if they have a great location, they are "visible" enough. Those of us who are either "other than store front" based or have horrible locations know that we don't have that "so-called" advantage, so we don't rely on it. (It's actually a false notion, anyway - in my opinion. Yeah, it helps, but shouldn't be relied on...)
We stay visible by being "in their face", not in a rude way, but by being everywhere they turn. There are a number of ways to do this - postcards, newsletters, newspaper articles, public speaking - anything to keep your name in the forefront of the customer's mind.
So, when they do need your services "YOU" are the one they think of. I call it "mental market share."
And it's in those postcards, newsletters, articles, and speeches that you give them the notion that they need your service more and more. Some have called it "cleaning out your drawers" or "from the shoebox to the shadowbox" or "framing your memories" or...
by the way, has anyone seen the PowerPoint presentation available from the PPFA? It is incredible! I will be using it this Saturday at a business expo.
Just another way of staying "in their face..."