In fact, she was so busy chasing down new customers she completely overlooked her existing customers as a source of additional business. Your existing customers and clients already know and trust you. They experienced proof of your ability to help them solve problems when they bought from you the first time. It's easier for you to get more business from them than to get business from new prospects. It's also more profitable than business from new prospects because you get it without any advertising expense.
Some businesses have natural repeat sales built into their operation.
Most MLM companies sell consumable products that periodically need to be replaced. A website hosting service collects a new fee at regular intervals to keep your site up. These replacement needs automatically generate repeat business. You can do this even if your business automatically generates re-sales. These new products must be related to what your customers originally bought.