Have you ever had to redesign a site so that it's more SEO friendly? How can you do so without eliminating the good amount of traffic that you're receiving?
There are a few things you should take into consideration. Ammon Johns contributes to the Cre8asite Forums thread with a lot of good information, including the fact that you should see where the healthy traffic comes from and ensure not to screw it up.
When you redesign your website, you should focus on improving the user experience for new users and existing users without breaking that which works well.
Ammon adds that there are changes that you can make that are imperceptible to the average customer. But you should look at your analytics to see what works well for you.
DianeV suggests that you take precautions because if you're doing well already with conversions, you don't want to do anything that could reduce the conversions.
And the bottom line isn't necessarily just to get higher rankings; it's to increase the sales. That means, necessarily, ensuring that the current successfulness of the site isn't hindered. So, unless you have a sure-fire way to increase sales without having to preserve whatever is currently causing conversions, I'd suggest treading very lightly indeed.
It's important information. You should not make any visible changes to the site without understanding what drives the conversions and whatnot.
Forum discussion continues at Cre8asite Forums.