The earlier versions of the firmware on the TP link had no facility to enable ping the router – very annoying for quick and easy connection diagnostic work or monitoring.
The lastest firmware for their routers enables this feature to be turned on.
Go to the TP link downloads page http://www.tp-link.com/support/download.asp download and install the latest firmware.
Once it is loaded login to the router drill down under management to the remote access section check on ICMP (ping) and then save and apply.
You will now be able to ping the router immediately without having to reboot.