thanks all for the comments- I got my original validation in Sept of 2005 and had renewed Sept 2006 good till sept of 2007. Since I am flying an N-registered a/c I don't need the validation, didn't renew it, but would still like to maintain the validation for possible future use.
Seems like no one has a definitive answer including the CAA!
I will just have to show up and ask to be revalidated and see what happens!
I have also been told that as long as one is flying outside of SA one can renew