This is a simple CGI script for OpenWRT (tested on Attitude Adjustment) to allow reconnecting to the Internet / router reboot from LAN without any authentication.
Download reconnect to /www/cgi-bin and make it executable by entering
wget -O /www/cgi-bin/reconnect http://github.com/zyv/openwrt-reconnect/raw/master/reconnect
chmod a+x /www/cgi-bin/reconnect
Open http://192.168.1.1/cgi-bin/reconnect and click Reconnect (substitute your router's IP if appropriate). Your WAN Connection will be torn down and re-established.