There are two ways to agro her. The primary way is her door in the left hallway opening on its own. When it opens, you have to look through the left hallway camera and close it using the button next to the door. She can also be agroed at nearly any time if you squeeze your stress toy too rapidly. I've found that the safest way to regain sanity is by squeezing the toy once every one or two seconds. She becomes more sensitive to the toy as the nights progress. If you get the animation of her peeking through the door before her jumpscare, you can in theory mash click to close the door on her, but in the current patch it is notoriously hard to mash the door shut