Refreshing pages after HTTP redirects

Well, I've gone on to the next step of my project.

I've finally moved to a more structured development approach, treating 
web pages as forms as having them call a central cgi script that 
dispatchs calls to other scripts, and then redirects the client to the 
next step.... Basically, a mini servlet idea.

So, in my pages, the forms call a central script, say 'foo.php'.

foo.php redirects the client to a webpage that shows a "Please wait, 
processing your request' page, using http header rediracts.

When processing completes, foo.php sends another http redirect header to 
the client to redirect it to the next step. The problem is the following...

Say the client is on a.php, which renders a form that calls foo.php when 
submitted. After processing, foo.php redirects the client back to a.php. 

( a.php has a search form, and displays query results from the DB ).

The problem is that a.php is not refreshed, it shows the last value. 
I've tried various http caching headers, and other items, and I can't 
seem to force a refresh when redirecting back to a.php.

Is there a header that says "Go to a, but refresh it too."?

-Daniel