I'm here to answer a question that I get asked all the time: is it possible to get out of the friend zone? But before I answer that, I want to talk about what you should say first and why, because that's way more important.
When a girl says "let's just be friends," there are two responses you should consider. The first is: "no thanks, I already have plenty of friends." The second is: "I don't have platonic relationships with women."
Both of these responses are meant to be said respectfully. They indicate clearly what you're interested in and show that you aren't the kind of guy who's going to give her free attention in a one-sided friendship. You're showing that you have standards and that you aren't the kind of guy who's going to be a puppy dog for a girl who isn't attracted to you.
By saying one of these things, you're indicating that you're interested in her sexually and that you won't accept anything less than a romantic relationship. This will save you time and prevent you from having hope in a mostly hopeless situation. It will also make it very clear where you stand and prevent any secret intentions.
If she is interested, congratulations, you passed the test. If not, you've made it known that you have enough female options and that you're not desperate. You've also forced her to make a decision instead of putting you on the back burner.
So, is it possible to get out of the friend zone? Yes, but the best way to do it is not by being a traditional friend. The best way is to live your life, improve yourself, and date other women. A woman who has friend-zoned you might come around and want what she can't have when she sees you out and about dating other women. But you can't count on that.
The key is to have respect for yourself and to say that you won't accept being in the friend zone if you don't want to be. It's not about being mean or chauvinistic, it's about having enough respect for yourself to say that you deserve a romantic relationship.