Should I hope for this promotion, or should I give up?

Basically, I am 17 years old, and I have been in my current employment for just over 2 years now. I am one of the longest running staff members there, and my manager has considered me for a promotion. She has said that I am the best at what I do, and that I am a valuable asset to the team. A few months ago, she had set some targets which had to be met before I could be promoted. She said we'll meet back in about 2 - 3 weeks, however this never happened. I asked her about a week ago whether or not the promotion is still available, and she replied that it's still on the cards. She also said that she'll hold another meeting the next time I am working to review my progress. I've been in about 5 times since, and she has not said a word about the meeting or anything like that. My place of employment is currently experiencing a loss at the moment, however being 17, I am on minimum wage, and to promote me is 30p extra an hour! Do I keep "pestering" my manager, or do I give up hope? Any comments greatly appreciated. :)