How do I pre-fill some fields?

I need to create a form to allow people to enter data for multiple workshop events. I now have a form which allows a user to select their name, city and state date, time, location from dropdown menus. This works great if someone is entering a single event, but if they need to enter multiple workshops, they have to repeatedly select their name, city and state. Since this information will be the same for each event and since only the time. location and date will differ, how can I have those specific fields remember the options last selected by the user? It would be awesome if the user could add one event, hit Submit, select 'Add another event' and find some of the fields pre-filled for them. Is this possible and if so could you explain - as if to a 5 year old, please! - how to do it? Thank you so much for any help! :)