How to change the Slug URL in Blogger

I'm not sure exactly which of these caused it to work, but recently I made several changes:

• I transferred the blog ownership from a Gmail account to a Google Apps Account on the same domain.
• Instead of forwarding the naked subdomain with a CNAME record to ghs.google.com, I switched it to use a 301 redirect from the naked subdomain to www.
• I added MX records to the naked subdomain and started using Google Apps Mail.

... and then suddenly all my comments appeared again. It has been about 3 weeks since they first disappeared.

On the edit posts screen, click the label to select all posts with it applied and add the new label to all of them (Label actions -> New label). Then just delete the label.