One of the most challenging duties you will face when working in sales is replacing lost business. Maybe you had a large customer that went out of business. Management changes within your account may have forced business away from your company. There could have been a service or product issue that simply could not be resolved, so therefore you and the customer went separate directions. Whatever the case, this will happen to every salesperson on some level in his or her sales career.
This is an event you have to plan for when working in a sales capacity. You need to plan on losing a certain portion of your business each year and factor in a sales growth rate that will compensate for this loss. Consistently searching for and opening new accounts on a regular basis is the best way to combat the issue of replacing lost business.
You can not wait until business within an account has already been lost before taking action. If you are running a sales territory with few or no customers in your sales funnel, you are heading for a "crash" landing. Many salespeople represent products or services that have a lengthy sales cycle, so waiting until large account goes "south" is even more detrimental. Depending on the sales cycle within your industry, replacing this lost business may take up to 3 to 12 months.
No matter how good your business is in the present, you have to move forward with a plan to gain new business. Replacing lost business will never be easy (or welcomed), but it can be managed if you have an effective sales plan in place.