For a lot of business, staying in contact with customers is somewhat awkward, especially if considerable time has elapsed. Often customers that are no longer visiting your business are simply classified as lost.
The reality is that there could be a simple reason why the customer hasn't been in for a while. Whatever the reason, it's good for you to know, especially if the customer was with you for a long time.
It only takes a few minutes to make a quick telephone call or to drop a past customer a quick letter to say hello. There is nothing at all wrong with mentioning that you haven't seen them for a while and you were wondering if everything was OK with the products that you sell or the services that you offer. You may find that there was a problem that you can rectify easily over the telephone in a few seconds. It may be that a competitor has opened up that is better located or better suited to meet the customer's needs. It may be a simple financial matter. Whatever the reason, you need to know.
I have seen a lot of businesses dig out their old customer files and start doing a bit of a ring around, and all of a sudden they have attracted a pile of new business, simply because they have called at the right time.
Other business owners have found that their accounts department has continually been messing up the invoicing, to the point where the customer simply had enough. You may find that if you have reduced your profile in the business, your customers aren't as happy to deal with your staff - they started using your business because of you, and if you aren't the one that they deal with now, they may decide to go elsewhere.
Contacting 'lost' customers is an interesting exercise, to say the least. It may be a little confronting for some people, but for those that are serious about customer service it's a very good exercise that will pay for itself many times over. Remember, also, that people love to hear from the boss or the owner of a company.