You need to teach her to lower her head for you. When she learns that, then start using that cue, to teach her to keep her head lowered for bridling.
I teach to lower the head by putting light pressure on the poll, and releasing, as soon as the horse even lowers his head just a tiny bit. He will give you more and more as he understands what the pressure means...never release until she lowers her head. Practice several times each day. The more short sessions you can have the quicker she will get the concept.
Since she seems to be fearful of the bridle as well, I would do alot of desensitisation around her face. Rub her with your hands all over her head, rub her with the bridle, etc. She needs to get really quiet before you really attempt to actually bridle her again...and she also needs to know how to lower her head.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."