There is a poor man's fix all you need is a lighter, wire strippers, electrical tape and vicks vaporub.
Clip the bad sections off the plug and sensor bar cords leaving both disconnected. Strip an half inch off both ends then separate the two wires on each end. Use a lighter to burn the insulation off each wire then twist it with the similar wire on the other end. use electrical tape to seal and separate the twisted wires and seal them all together. To prevent her form doing it again all you have to do is rub the vaporub on the cord. The scent and taste will deter her.
As mentioned, the old Wii sensor bar should work as well and the sensor bar only produces a light for the controllers to figure out the relative position. Either way, for replacement it would be better to get a WiiU sensor bar instead of the Wii unless you can confirm that they work. If no local store has one, you should be able to buy a replacement one on Nintendo's site as well.