Permalinks Should be able to Retroactively change

When you go into the control panel of your WP blog, and you change the type of permalinks, you should be able to retroactively update the location and web addresses of your current permalinks, OR be able to make duplicate copies, one at each format everytime you change that way old links will continue to work, and new links will have the new permalinks format. Currently, when you update the permalink system it only applies to posts following the update and the current links so it causes many links to be broken.