I absolutely hate having to catch mine. Haven't had to for two years, and dread the day when I have to again.
Remove everything from within the tank (except for substrate, if you have it) and above the tank. Drain the tank so that its dorsal fin starts sticking out of the water. Then, as quick as you can, net her out and put her wherever it is you're putting her next. Some people recommend using a wet t-shirt to move big fish, but unless you can physically get in the tank to catch her, and then hand the shirt to somebody outside the tank, I don't think its feasible.
Good luck.