2.2.9 (not sure starting with which revision at this point) includes automatic reconnect for WiFi. I've added it because I run WiFi for my primary home hub and it had some connection drops. This automatic reconnect does exactly what you describe - shuts down WiFi interface, reloads the kernel module, and starts WiFi interface back up, forcing a new DHCP request.
The restart button mentioned in this post did the trick for me every time, but it's a sample of one.
