There was a recent article from USA Today that provides some insight on how any small business might increase their business. The article begins by describing the scenario of a struggling new small business and first suggested that the new owner contact SCORE. If you've never heard of SCORE, the article describes it as a kind of Peace Corps of entrepreneurs that give free counseling and advice to small business owners. If you visit their site you can also sign up for SCORE eNews and SCORE Expert Answers.
So what advice did SCORE give this struggling new business? The advice was simply ask your customers or prospective customers what they want and give it to them (within reason of course). You can read the whole article for the specific ways they suggest to find out what they want and you can probably come up with a few more of your own. One other excellent idea suggested is to find out why you've lost customers. This will not only provide useful information so you don't lose customers in the future but also might entice some of these customers back since you've shown an interest in their thoughts.