Just because you lost the sale does not mean that you stop marketing to the prospect. You always keep everyone you come in contact with in the sales loop. You never know when the prospect changes his or her mind or if the company they choose over you went out of business or stopped servicing the prospect properly. It might be as simple as the other company raised their prices. It’s even better if after a few months you call the prospect to see how everything is going. Think about it.
You just never know and this is why you keep everyone in the loop at all times.