actually, i think the highlights are about bright enough.  if you want to make them brighter, i suggest making them reflective and giving them something high contrast to reflect. what's not working so well is the relative brightness.  you've got blonde hair that's about as bright as the highlights over the eyes and next to the highlights.  i'd advise against that.  you've got a perfectly black background, which means the eyes are just a bit more black.  i'd advise a background with color or something happening, so that the only smooth pitch black is her eyes.  i'd get her hair out of her eyes or make it lank.  because a cute set of bangs that hang over the eyes just says you aren't feral enough to either stop caring about grooming or to have a hair style that doesn't obscure your view of your prey.  she's awfully tan as well.  

artists use the classic red, white and black theme for vampires because it works well visually.  with a red background, pale skin, and black hair and eyes, the eyes would be the darkest, blackest aspect, the highlights would show off well, and the contrast would be dramatic. 

but it would be very, very typical.  i'm not suggesting you lose your artistic vision or individuality. i just think you should understand why the typical works, so you can still have its strengths.   everyone is suggesting brighter highlights, and i find 9 times out of ten that people say you should make something more x, when really, the problem is making everything else more -x.  contrast is key to drama, drama is key to a sense of menace.