Although it isn't possible to resend the same eNotice to a new list of recipients, you can copy the contents to a new eNotice and send that one to additional users.
Find the eNotice in the "Sent" folder on the eNotices tab. Hover over the message and click the "Clone eNotice" button. This will create a new eNotify message with identical content to the original. At this point, you can edit the content if you wish, or send the cloned message to the additional recipients.
When you clone an eNotify message, the original recipients are copied as well as the content. Always double-check the recipients and remove anyone who's already received the message (unless you want them to get it twice!).
Note: Cloned messages have independent statistics and tracking data; you cannot combine tracking data from two separate eNotify messages. If you need to compile the tracking data for one or more messages, sort them into the same folder and use the Folder Stats button to view the cumulative tracking data.