You cannot add new user data to an existing segment. You can only create new segments. In your ad settings in Yandex.Direct and Yandex.Display you will need to replace the old segment with the new one you wish to use.
To see what options you have for a segment, click on in the row next to a segment. You can rename a segment, create a similar users segment based on it, or grant access to this segment to other Yandex.Audience users.