New event with participants from other event (copy/reuse/sequence event/duplicate)
You can copy participants from an existing event into a new event in three ways (not including the address book):
From an existing event (no account required)
Open the event from which you want to copy the participants into the new event. Right below the event cover picture and title, click on the gray 'options' button. Here you will see two options to choose from:
duplicating an event, most of the things of an event are copied (title, description, date suggestions, location(s), participants). In this case a new event is created, so there will be no responses from participants or comments.
creating a new event with current participants, everything is still blank (no title, description etc.), but the participants are already filled in at the end. This way, you can create a completely different event with the same participants.
While creating an event (logged in with account)
If you have an account and are logged in while creating an event, you can click the options button in the invitation step under the 'Invite via email address' section. There you can choose to select participants from previous events (as long as the events have not yet been deleted).