What size tub? Anything bigger than a shoebox and she's going to be overwhelmed. With a 6qt, you only need one 4-6" clay planter saucer(or plastic saucer, whatever the store has) and a small water bowl. Newspaper in the bottom. You can crumple up some paper towels to take up space too.
Get the temperatures up to about 94 on the warm side, cool side can stay where it is. Leave her completely alone for a week, don't even touch her to clean the tub, just pour water in the bowl if needed and walk away. Possibly cover the tub with a dark pillowcase and stick it in a quiet place.
After a week is over, pre-scent for about 20 minutes or so using a live large crawler mouse or small hopper, eyes open is fine. Leave it in a tub next to the snake's tub for awhile in the dark. After the pre-scent time, put the mouse in the tub, close the lid, and leave it alone ALL NIGHT. Do not disturb at all.
Usually, they take them at night when nothing is around and the room is completely dark. I've had good luck doing this with stubborn babies.
OP: Follow this advice to the letter and things will more than likely turn around for the snake
~~McKinsey~~
"Men have forgotten this truth," said the fox. "But you must not forget it. You become responsible, forever, for what you have tamed."
~The Little Prince; Antoine de Saint Exupery