This is something we always discuss with clients when doing a redesign. It is essential to protect your "SEO Juice". This can be an oversight on many redesigns, or companies just don't provide it as part of the project.
Columnist Marcus Miller explains how to make the most of your website redesign so that you not only preserve your SEO efforts but embrace the new opportunities that come with relaunching a site. A new website should be an opportunity to improve SEO, conversion rates and digital marketing as a whole. Unfortunately, it can also be an invitation for disaster — if the right steps aren’t taken to ensure a smooth transition from old website to new, you can damage the SEO equity your site has worked hard to build over the years.