Jim,
It is important and profitable have continued marketing to your existing clients. But, A business will naturally lose current clients due to attrition.
Clients will move, their kids will grow up,they will replace carpet with wood etc..
Therefore, A business needs a balance of; marketing to existing clients, prompting referrals and cost effectively marketing to drive new clients to you.
A thriving business needs new clients to replace clients that drop off and to have continued growth.
Don't give up on driving new clients to your business.
-Dave