Not at this time. You would need to cancel the user from the waitlisted session and then add them to the dated session. Although this would be a great feature to have, you may want to put in a tracker issue on it.
As Scott said, you cannot do it directly at the moment.
However, as a teacher, you can cancel the user's waitlist signup (make sure to check the "Suppress email notification" checkbox) from the attendees list page.
Then you can go to the real session and add the user to the list of signed up users.