As mentioned above, grab a single rear line and reel it I enough that the kite will flag out on it. In the process it may spin and look like it's getting worse but generally it comes out fine. Some times if you grab the wrong rear line, it will still come out but with a line invert (front and rear lines twisted) but will still be usable and get you back to your launch.
Occasionally, especially with race style kites with long thin bridles, you'll end up with a bridle line behind a wingtip. Usually if you fill the kite over and reverse launch, it will shake out.