I have a few techniques for this type of situation:
1. Accidental Ambush - Keep up to date with her social networks/friends and find out when she is going out with them and to where. 'Accidentally' bump into them and start talking. It will be a perfect opportunity for you to reveal your true feelings for her.
2. Postcard - Send her a nice hand written letter apologising and explaining your feelings. Send it to her house. Being hand written it still carries the personal touch but gives her time to think over how she feels and respond to you. She won't feel rushed especially if you wrote it in a way where it's clear you're just telling her something and not expecting a reply. Only do this if you're currently friends.
3. Personal - If you were once close the chances are you know where she lives. Knock on her door and talk to her. If her parents answer, ask them if she is home, if she is not, ask them to her you passed by. Only do this if you are currently good friends. It would be creepy otherwise.
4. If you're at the stage whereby you've fallen out of contact for the most part and rarely communicate, you need to talk to her as much a possible in school to build up a friendship and tell her how you feel.
You want to get back with her. Asking her to the cinema is ridiculous. That demonstrates a want for friendship and does not reveal your true intentions. It's actually rather deceitful. Tell her how you feel and the dates can follow. You don't do courtship first.
Although, it does sound just like Lee1985 described above. In which case you could do the reverse annd say something like "I know you don't see me in the same way I see you etc... but I wanted you to know that I ___________ . I hope you respect this and I respect you in thinking ____________. " - Something along those lines. The aim would to reveal your feelings to get them off your chest but at the same time acknowledge it's a lost cause.