If you have saved the segmentation criteria that you have used to create a segment, you can reuse this to create a new segment. The newly created segment does not necessarily contain the same contacts as the other segment. It contains an updated list of contacts matching the same segmentation criteria.
If you want to create a segment containing the exact same contacts as another logged segment, use the Segment, Reuse Logged function.
Open the 
Segment window.
Press F3 to enter a new segment.
In the No. field, enter a new number for the segment, and in the Description field, enter a new description for the segment.
Fill in the other fields on the header. For Help about a specific field, click the field and press F1.
Click Functions, Segment, Reuse, Criteria. The Segment Criteria window appears.
Select the segmentation criteria that you want to use to create your segment, and click OK.
The program fills in the segment line with a list of the contacts currently fulfilling the segment criteria.
Click Functions, Segment, Go Back, if you want to go one step back.
Creating Interactions for Segments