What is the number one reason donors become "one-time" instead of "recurring"?
Donors cite the number-one reason for ceasing their support as this: It was the way I was treated by charity, from not being thanked to an avalanche of needy appeals.
You need a thank-you message that says to your donors, "you matter," and, "let's start a conversation." Think of the old marketing adage: It's cheaper to keep a customer (donor/supporter) than to find a new one.
Here's an example of a unique way to thank your supporters from Save the Children.