First, I wouldn't use the periodically_call inside the refresh div. I have the feeling that it will vanish at the first call as it will be replaced by the content if the update.
Put something like
You may have to check some option to make sure this piece of code will be evaluated.
Pardon my errors or typos, but Im on my mobile without access to reference material.
You should find some info on periodacal on www.prototypejs.org