[Plugin: Emo Vote] Change votes?

Sometimes people change their minds. Is there any way to make it so that people can change their votes once they have voted?

From an interface point of view this should be simple: If you have voted on a post, one button is already checked. So instead of the controls being not clickable, you could just click on a different one to register a different vote.

It would have to erase your old vote and replace it with the new one, which means you’d have to keep track of each user’s vote on each post in the emo votes database table.

I’m not sure how it works under the hood so I don’t know if this is easy or hard to do. Any ideas how to make this work?