I started a subreddit that has 9k subs, I need ideas to get more?

I started a subreddit a month ago and have driven the subs up to 9k but im kinda stuck. I have used all the free promo subs, I have done as much crossposting as i can. I have been banned from one sub because I crossposts to much. Now I'm lost on what I can do to drive more traffic to it. Any body got any ideas?