There is an online petition called, "Bring Back DC Nation". The goal is to reach 10,000 signatures and right now the petition is at 7,986 signatures. Just in this short time tons of Young Justice fans have already been signing and passing along the petition via internet.
I'll be signing it as soon as I'm done this with this post. I'm glad this was created since hopefully this will be another way Cartoon Network will know that Young Justice has a huge following and it isn't right to keep putting a well-written show on hiatus when we just got off one. Maybe soon they'll realize to think twice before rudely putting off YJ again.
*Here is where you can sign the petition*: