You can modify the Invitation Email to be a save the date and email your previous guests right from your event.
Set up your event as usual with your event details and banner graphics
Click Template Setup > Invitation Email
Change the Email Title and Subject line to "Save the Date". These fields are above the text editor.
To remove the accept and decline buttons, click the button in the editor, and then click the trashcan icon in the popup
Save your template changes
Follow these steps to send the email to your previous guests.
Once you have sent your save the date, return to the template and click the link to Restore Default Page
Other articles you may enjoy:
Invite a past guest to this year's event
Updated 12/12/17