This frightening scenario could be changed by planning the optimization before redesign. Here I am outlining key mistakes that you should avoid while re-designing the website. Please visit here : http://www.brainpulse.com/articles/web-development/why-redesigned-websites-fail-to-deliver.php
When designing a website here is the best piece of advice I have heard in a long time.
You have to "satisfy the cat".
Check out this youtube video: Satisfy the Cat, a.k.a. User-Centered Design
It's a great way to look at things when developing a new site.
Regardless of whether it's new or updated, websites will neglect to convey expected outcomes if it's outlined without considering key factors that effect Search Engine rankings factors. I have seen numerous advertisers neglect to design SEO while launching their recently overhauled website. This prompt extreme fall in site's natural hunt ranking, activity, and income. Questionably settled SEO components could destroy your site design improvement best practices that you had so painstakingly incorporated into your old website.