All businesses lose some customers through no fault of their own. Customers move, retire, die, etc. You need new customers just to stay even. Therefore, no matter how good your business is today, you need to be always trying to acquire new customers. There is a right way to attract new customers and a wrong way.
The biggest mistake I see businesses making when trying to attract new customers is making a special offer to "New Customers Only." I have seen ads that offer special discounts to new customers, extra free services to new customers, etc. How do you think that makes the existing customers feel?
If I have been a loyal customer to a bank for 10 years and I see an offer for a higher CD interest rate to new customers, how am I going to feel? If I have been a loyal customer to an auto repair business for 10 years and I see an offer of a free oil change to new customers, how am I going to feel? If I have been a loyal customer to a CPA for 10 years and I see a special discount for tax returns preparation to new customers, how am I going to feel?
When customers have been loyal to a business, they deserve the special treatment. First, they feel they should be rewarded for their loyalty. Secondly, as a business owner, you know that you have had a loyal customer. The new customer who comes in for the free oil change may never come back again. Do you want to risk making a loyal, long-time customer unhappy for the chance (and it is only a chance) of getting a new customer?
My advice is to always take care of the known factors first. Take care of those who have been taking care of you. It takes a great deal of good business practices to keep a customer for many years. Don't let all that hard work and effort go "down the drain" on the chance you may get a new customer.
If you want to offer something special, offer existing customers an incentive to refer new customers. That is much more of a win-win situation.
Remember the old saying, "A bird in the hand is worth two in the bush."