It takes 4-½ times the energy, resources, and staff to secure a new donor than to keep the donor you have. Perhaps you should pay a little less attention to securing new donors and pay a great deal more attention to those who have shown their friendship and support for you.
Let’s say you lose 40% (low for many organizations) of your donors each year. For every 1000 donors, you need to pump 400 new donors into the pipeline.
Read this piece that follows (PDF) for some helpful tips on how to keep your friends.
(And by the way, if you don’t carefully monitor your attrition— you will be on the losing side. Keep tracking it. If it’s more than 40%, you have reason for concern.)