well just like Young Justice, Green Lantern the Animated Series did not get renewed for another season. I'm just getting all the information so I don't know all the specifics as of yet, but as with Young Justice if it was getting another season we would have heard it by now.
As I said in the Young Justice cancellation thread, maybe it was poor toy sales (Toy deals are the banes of a lot of cartoons), nevertheless it looks like this shows axed. I'll update if I learn anymore.
more info from the World's finest website:
Cartoon Network has issued a press release overview of the network’s 2013-2014 upfront presentation, citing new programming initiatives and returning titles. The release below confirms a Summer 2013 debut for the new CGI-animated series Beware the Batman and an April 2013 debut for the new Teen Titans GO! comedy cartoon series, both additions to the weekly DC Nation programming block which airs Saturdays at 10:00am (ET/PT) on Cartoon Network. Additionally listed, current DC Nation titles Young Justice: Invasion and Green Lantern: The Animated Series are both absent from the “returning shows” list featured in the press release. Please note no production information or confirmation on status from the network on either series has been released.