Make sure when you put her in a tub to soak that you monitor it at all time. Don't walk away as you never know what might happen.
I have had my share of stuck sheds over the years and what always works is luke warm water (80 degrees is a good number giver or take a few) with paper towels on the bottom. Don't fill it more than half way to 2/3 the height of the snake's body. Let them soak for 20-30 minutes and if the shed isn't off by then you can start assisting gently.
In the future a wet/humid hide box solves all these issues.
Snake Discovery has a great video on how to make a humid hide