If your Office 365 tenant has been migrated, you may have noticed that there is 2 public web site: the new one and the old one.
If you used the previous public web site, you may don’t want to re do the work on the new public one.
Don’t worry, Microsoft is offering a free migration tool to move from the old public site (from SharePoint Online 2010) to the new one (on SharePoint Online 2013)
All the details are published here http://community.office365.com/en-us/blogs/office_365_technical_blog/archive/2013/07/10/upgrading-to-the-new-public-website.aspx