Or you could use your iPhone as the remote via the Apple TV Remote app - less chance of losing it!
Btw - I just used the Lightblue Explorer app to find a friends lost Fitbit. It displays the Bluetooth strength of signal of any transmitting Bluetooth device and can be used to get closer to the lost device (Cold, warm, hot!). But I think the ATV remote only uses infrared and only when you press a button.