I had the same problem after the updat. Try rebooting your system by unpluging the modem and then plug it back in. Takes a few minutes for the network to be reestablished but after doing this I got my airplay icons back.
Since the update certain apps which stream films,videos etc no longer display through Apple TV they worked perfect before but videos and films down loaded from itunes streamed from iPad & iPhone still work fine any help ??
Turn off home sharing on both the Apple TV and your computer, then sign out of ITunes on both as well. Reset your net work router. Once this is done sign back into both iTunes and home sharing on both devices. You should see all of your media.