You have cloned your event and would like to access last year's data to email your contacts.
Last year's event is still available from Events -> Events Overview (if you have cloned), by selecting 'Show Inactive Events'. Once there, click on last year's event (and you will see that the event name appears in the header area of your admin, near search).
You can now access email management from the Email tab. You will notice three options in the Email menu: Lists, Compose, Templates.
Choose Compose to send an email to a specific group of users, such as registrants, sponsors, team captains, volunteers, donors, etc. by selecting them from the To: drop down menu.
Select "Participants" or "Donors" to send an email directly to last year's constituents.
NOTE: Last year's website banner (from Website - Settings) will appear at the top of the emails. If you do not like this, you can update that to your new banner before sending the emails.