Licences and ratings are revalidated in different ways.
A RATING is revalidated by taking a flight test, or in the case of the SEP rating, by experience. The revalidation requirements for a rating are the same, whether it's attached to a PPL, CPL or ATPL.
LICENCE revalidation is purely an adminstrative process. All JAR licences are valid for five years. When your five years is up, you fill in a form and send the CAA a cheque (for a change!) and they send you a new licence. No flight test or minimum hours are required, although you do need to have a current medical and at least one current aircraft rating in your licence when you apply.
So nothing fundamental changes when you get a CPL - you just have revalidate any type or class ratings you have, renew your medical and apply for a new licence every five years.
Hope that helps!
Al