If you enable the Monitoris tool, in the Admin->Settings->Advanced will be displayed a new option: Monitoris will monitor a post if no activity for

You can use the option to decide how many days the cron job will check for new activity for a post. For example a post, was published a week ago and in the first 2 days the post was commented and liked. Then no more activity. So, if you decide to limit the check for 1 days, the post will be excluded, but will be included the old posts which have new comments and likes every day.

This is valid even if the user have deleted the post from the social network. You will save resources if you will limit the check.