I think there's a possibility that there really isn't anything that they can do. I don't mean that in a negative way, only in that they've already tried so many different ways to increase the general ratings of the show and none of it has worked. People know that it's out there but they're just not interested.
They've adopted familiar and well known storylines, such as the nWo inspired faction wars & corporate power struggle angles that they've done for such a long time. They've invested millions of dollars in bringing in some of the biggest names in the industry for the hopes that fans will tune in. They've brought in Hulk Hogan, Kevin Nash, Scott Steiner, Booker T, Kurt Angle, Eric Bischoff, Jeff Hardy, Rob Van Dam, Sting, Bubba Ray & Devon, and others. They've tried to basically recreate ECW for a while without actually being able to use or even say ECW in hopes of generating interest. They've gone the way of tits & ass segments, such as Lacey Von Erich's "striptease" segment, matches with lots of blood, promo segments with lots of cursing, and so on and so forth. All in all, none of it has really panned out in terms of ratings growth.
As someone else pointed out, and as others have pointed out numerous times over the years, TNA needs to develop its own identity. The majority of the past 5 years, TNA has been built around veterans that were big stars in WWE, WCW or both companies. They wanted to capitalize on the fame those wrestlers had made in the bigger companies and use it to increase their own audience size, often at the expense of the homegrown talent they've already had. In the past several months, however, TNA has moved more away from that line of thinking. They've been making the younger wrestlers, the homegrown talent the main focus of the company. Now, they're starting to do their own thing with their own guys just as WWE & WCW did before them.
And like those two companies, TNA is going to have to put in hard work, time, energy and dedication to get the job done. WWE wasn't always the huge mega force that it's become in wrestling. It took time, years in fact, for things to really just fall into place and for them to ultimately get to where they've gotten in the grand scheme of things.
I don't think there's going to be any quick & easy answer for TNA when it comes to audience growth. Sure, they'll pop a rating every now and again but they always wind up back drawing in the low 1s. It's good to see that they're FINALLY putting focus on their homegrown talent and that's what they should've been doing for a long time. And while people know that they're out there, they aren't ingrained into the public consciousness as the WWE is when it comes to wrestling.