How do I approch a girl that already knows I like her?

You just answered your own question. Approch her and just tell her how you feel. I mean she already knows that you like her so what do you have to lose. Nothing. If you are good friends then just be honest with her and tell her how you really feel. Keep your best judgement on high just in case she turns you down. But i say what the hell, walk up to her and ask her to go on a date to dinner and a movie. Or just don't go nowhere find some place quiet and talk to each other. When you are open with yourself and others you will gain more respect.

You may wish to approach her just how you would to a friend. Since she's already aware of your feeling, you can look out for encouraging signs before you decide how much or how fast you want to let go of your feelings. I believe if she feels the same for you, she will show through her actions. However, do not rush for fear of scaring her away .

If she already knows you like her then you need to think if she has been avoiding you or if her conversations with you are shorter,these might be signs that she isn't interested. Other wise if things haven't changed or gotten better then perhaps she is interested in you too. So it should be easier for you to do.

Since she already knows you like her, be straight forward, be your self and always remember, she's not the only one in the world... even if she denies you, I'm pretty sure there are plenty more eager to meet you. Last friendly advise... be confident and never arrogant.

Just say "hey...wanna grab a coffee sometime?" Then go from there.....if she says YES, then you'll know she likes you back, if she says no, then it is time to move on.

Buy her chocolates and red roses. Tell her your feelings even if she has already known that you love her. ^_^ ^_~ ^o^

just go up to her and start a coversasion

with great caution I'd imagine..maybe she doesn't like you as much as you think *g*