If you delete and repopulate, the links that haven't changed will be the same as long as they haven't been customized after autopopulation, however there won't be 301 redirects in place from the old urls to the new urls for the urls that change. If you export, modify in CSV, and import, then 301 redirects will be in place. Alternatively, contact me via our support desk at
http://www.websitecm.com/support/ and I can send you a file that will write all current links to the url history so they will 301 redirect however they get changed, and then you could use the delete and re-populate (though I would discourage the use of it on a live site still).