No. Don't go into a long drawn out "bugging" session. She'll just learn to ignore that , and you will teach her to be able to tolerate increasing levels of nagging wihtou being obedient.
If you ask her to back up, try this.
First, aske her to flex her head to one side , let's say the right, just a little bit. I mean , she flexes her head from the poll, so that her jowl kind of tucks into her neck. She will be softening on that rein. When she is soft on that side, make that hand kind of firm (to disallow her going forward) and put your legs on a little to ask for movement. I like to put the leg on more strongly on the same side as she is softened on.
THINK back, in your mind and body. Sit up very straight, maybe roll your upper body back a tiny bit, but don't roll back onto your tail bone.
Think of kind of "pulling" her back with your leg on the side that she is softened toward.
Get one step backward, with her soft in the mouth, and release. Good job.
Now, soften to the left, firm up your hand and leg on that side and "pull" her back with that leg (I dont literally mean pull, but rather think of your leg encouraging her to come backward with it, so you can even kind of brush your leg on her side , from front to back). one step backward, and release.
so , you get her to go backward by addressing her one side at a time. Softening in the jaw, asking for movement with the leg, and closing the door for forward movement with a firm hand, and thinking "backward", And rewarding for each good step.
If only I could show you! so much easier to do than to describe.