Otherwise you will hire the cheapest labor -which is yourself...and you'll never break free of being a freelancer.
My personal advice...the reason raising your rates isn't working for you is because "you don't get the work." This is key...if you need the work, you will never successfully raise your rates.
I have fetched $350/hr for SEM consulting...when you can easily hire an experienced pro for $50 and someone more experienced than me for $175. How do I charge that much? It's simple. My opportunity cost let's me turn down lower paying gigs.
The secret to winning a negotiation is going in believeing you can walk away without feeling like you missed out. If you can walk away....you are in the driver's seat.