Which theme replaced the more traditional memento mori theme in metaphysical poetry?

Carpe diem

Explanation:

The idea of memento mori (remember that you will die) was a common theme in poetry. However, this traditional theme was replaced with the theme of carpe diem (seize the day) in most metaphysical poetry. Both themes are strongly related, as carpe diem urges a person to fully enjoy each present moment. This type of mindfulness is usually achieved through an awareness of our own mortality, a concept that memento mori expresses.

The answer is carpe diem