What does your character think and do when they see their own reflection? Do they stop and fix their hair (guilty), wink at themselves, wrinkle their nose, shudder, etc.
Example: When Clementine passes by a reflective object, she instinctively smoothes out the top of her hair. If she's alone (or forgets that she isn't) she makes weird faces at herself and falls into deep, contemplating thoughts.
When Azra sees herself into a mirror/reflective object, she automatically straightens up and, if distracted, goes back to thinking about things that are actually productive–- as if seeing her reflection is like her catching herself being unfocused, in a way.
And that's way too many 'hers' in one sentance, but whatever.
When my character (Calendula) sees herself in a mirror/ other reflective object, she grins. She read somewhere that when you smile you feel a bit happier, so that's what she does!