What should i get my 15 year old girlfriend for her birthday? GIRLS ANSWER PLEASE :D?

I want to make her feel really special but i have no idea what to get her. I was thinking of getting her a silver necklace and earring set in a engraved box (link below) and then giving her 15 red roses (one for each year sort of thing) and maybe making her a cd. But her last boyfriend (who she hated) got her a silver necklace and i don't know if she really wants another one?? We have been going out for about 4months now and i want to make her feel really special, i need suggestions, PLEASE HELP!!!