Rear ABS Sensor Cable is broken

I'm new here. I have a 2012 Prius IV, and the cable that connects the Rear ABS Sensor to the car has broken at the part that connects to the sensor. I can still plug it back in, and it will be fine for a while, but it disconnects after some driving, just from working loose. The sensor itself works perfectly when it's connected.

I am not very flush, and I was wondering how involved a process it is for that cable to be replaced, and what you think I might expect to pay to have it done. Or, if there's some easy way to get it to stay connected, that would be great.