Refresh a segment
Go to Audience > Segments.
Find the segment you want to refresh and select Refresh.
In the Last updated column, you can see the date and time the segment was last refreshed.
Refresh a segment when sending
When scheduling a campaign to send to a segment or segments, a checkbox option is available to refresh segments before the scheduled send time. Select the check box to make sure segments are up-to-date at the time of send.
Refreshing a segment might delay a scheduled send by a few minutes.