Back In Stock Notifications only notify customers ONE time?

I love this feature on Zen Cart and it is the original reason for wanting to use this Shopping Cart.
I am just now noticing that if my Customer has a product on his/her Wish List...after I notify them one time that the product is Back in Stock...it ends there.
I need them to be emailed the Notification each time I have that particular plant available since at present time I have 25 people wanting a plant that I can only provide a few at a time.
Is there a way to make the Wish List...Back In Stock Notification continue to send emails until the customer actually removes it from their List?

My site is SRQHoyas.com

Thanks so much!
Joni