Be more open about your intentions. If she knows that you're interested in her sexually and/or are looking for a relationship then she won't friendzone you. Friendzoning is completely and 100% caused by not revealing your intentions and hoping either that she'll just spontaneously decide she loves you, or waiting for the perfect time that never comes.
Be more open and you won't get in the friendzone. Otherwise, this is probably game over with this chick.