Re "we need to “completely redo the website.” "

Suggest you refer him to http://www.theregister.co.uk/2011/01/27/website_content_is_most_important_detail/

And also remind him that the one thing supermarket customers really hate is to arrive ready to do their shopping and find that some twit in senior management has decided, with no reason whatsoever, to arbitrararily move all the stuff about. The new layout is no better than the old, just different. And, therefore, harder to use.

Both in web sites and supermarkets, some changes may be needed -- to cope with new products and seasonal demand. But for the most part you're best off leaving things the way they were unless you're completely sure that what you're changing to is a definite, functional not cosmetic, improvement on what you had before.