I have to say that for me it doesn't mean that at all. Sure, as a woman, I'm worthy of achievement, or the success I put effort into achieving. But by washing my hair in a certain shampoo, using a particular hair colour, that doesn't mean I'm worth it at all. In fact, I would go so far as to say that it's quite a defeatist phrase. By saying 'You're worth it' we are handing our power away. We are saying 'give me what I deserve', we are demanding rather than earning.
I do want be worth 'it', whatever 'it' is, but I want that in the context of me having created something, not just 'deserving' something because I exist. I want it in the context of having worked at something. I want to be worthy of what I've worked at and achieved.
Now, I'm sure there will be some who will describe this as an upper limit problem (as described by Gay Hendricks in The Big Leap), and maybe it is. But the truth is I love working at something, and if working hard is an upper limit problem, that's ok because I enjoy working hard. I love that whole experience of toughing it out and achieving something, pushing my boundaries as I challenge myself. I want that sense of achievement. I want to feel proud of what I've done. THEN I will know I'm worth it.