Sometimes you may want to send a single email from a blast Campaign more than once to capture newer leads.  Be sure to follow these steps first so that you don’t send anything to people who already received it.
1. Deactivate the campaign (assuming the first send of the message is complete).
2. Adjust the Lead Posted Date filter on the audience so it only captures dates after the date of your last delivery.
3. Pull the same message into the space, either in addition to or replacing the earlier copy. Set the new date/time.
4. Activate your campaign.