What's the best way of forcing cache regeneration?

Hi!

I am adding RSS to my website, and I would like them to be accessible
through a subdomain (this allows me to keep separate statistics).

So it’s quite easy, Apache redirects rss.site.com => /RRoute/public/rss

It works, however, I need a way of forcing the cache to regenerate when
I expire it.

For example, when I add a new article, I expire the cache. Then, someone
comes to rss.site.com/articles.xml, but the files doesn’t exist. Yet, I
am out of rails and it won’t regenerate!

Any idea?

Thank you!