Update: You can’t reload the configuration, but you can set the parameters on-the-fly, see second “Update” paragraph

It’s not really possible in Symfony2 to do that.

In production mode, everything (even the configuration) is cached, so you have to clear the cache with

app/console cache:clear --env=prod --no-debug

(maybe followed by a app/console cache:warmup --env=prod --no-debug)

to reload the configuration. In development mode you could experiment with shutdown() followed by a boot() from Symfony\Component\HttpKernel\Kernel or maybe loadClassCache – but all of this is not really that what you want.

What exactly changes are made to the configuration files? Maybe you should use different files for different environments or consider any other method to get those changes (via a simple Webservice or even a static file read from within a Controller).

Update:

I figured out that you can set your container configuration parameter on-the-fly via

$container->setParameter('parameter', value);

Have a look at the Symfony2 documentation.