I would imagine it would be pretty stressful to soak a leo, although I have heard of people doing it. The main areas of concern with retained shed is on the feet and around the eyes. These are usually the problem areas, but it is usually removed easily with a wet q tip as long as you catch it right away. The longer it is left, it constricts and it is harder to remove after time. When I have a stubborn foot shed, instead of soaking I just hold the leo and dip the foot in the water dish a few times to get it good and soggy 
Another option, which they hate, would be to give her a spray when she's getting ready to shed, or try moist paper towels under her favorite hide if she won't use the regular humid hide.
hope this helps!
-----

4.5 Leopard Geckos
1.0 Marbled Gecko
1.1 Red Eared Sliders
0.2 Siamese Mice