From Hackaday:

One of the common mods that popped up on the internet were ways of extending the range on the AR Drone. It normally uses a local Wi-Fi connection to your phone or tablet for control and video signals. Many found this quite restrictive and have gone pretty far in extending that range.

The first and easiest was just to set up a higher power Wi-Fi Bridge where you’ll be flying. The Drone only has about 15db of wi-fi magic in it, so anything stronger than that is an improvement. There were too many variations on this to delve into the details, but as you see, there’s not much too it.

The second method is to completely replace the Wi-Fi control system with a nice R/C controller. This will greatly increase your range as well as give you extra channels for triggering different attachments (usually lights).  I’ve seen two main methods used. One is called “MacGuyver mod”. This one is a plug and play kit that doesn’t seem to have much info along with it.

The other is called “MiruMod” and the creator has shared all the information they can.  You can find a parts breakdown as well as schematics, wiring diagrams, instructions, and software. [Miru] uses an Arduino Pro Mini or an Arduino Nano as a go-between from the receiver to the serial port on the AR Drone. You can see in the wiring diagram below that it is a fairly simple install, and all [miru] asks for is that maybe you donate some beer money if you appreciate his mod.