Stopping Repeat task due date alerts on the performance documents.

We have configured performance templates having having due dates for each performance task and also repeat alert enabled for each of them. We created the performance documents for the eligible population; due date alerts are working as expected.

Now, we want to change the due date for a certain task, and also stop the repeated notifications.

We know that we can change the due dates on the created performance documents using mass action, but how can we modify the 'Repeat' settings for the created performance documents?