I depends if you used a pattern for the foam. You can add a 1/2 inch to the pattern and that can work if you haven't added any features. Most of the threads are on covering the face with fleece, but the technique is the same, only most puppets have basic body forms, and unique patterned facial features.
It helps to search here, and some of the other puppet forums on the web. You can check out the Muppet Central thread
http://www.muppetcentral.com/forum/threads/covering-puppets-with-fleece.713/
You can check out the tutorial from Project Puppet
http://www.projectpuppet.com/servlet/Page?template=puppet-facial-features-tutorial#9
There is a great video series from StiqPuppets
Hope these give you the direction you're looking for.