People ask how to earn crowns all the time. There are literally hundreds of threads about it. You can find them by searching Google for something like "earn crowns site:forums.spiralknights.com". For example, here are two threads about it on the front page of General Discussion:
money and money and farm
Jue, 06/26/2014 - 04:51
#6252
so many threads
Jue, 06/26/2014 - 08:14
#6253
LOL Bopp. "For example, here are two threads about it on the front page of General Discussion."
I'm starting to wonder if OP is just messing with us on sock puppets or something.
Jue, 06/26/2014 - 09:00
#6254
and one of them
And one of them is Kingsamerb's, so we're not even talking about sock puppets here.
If you need money but are having a hard time surviving these later levels, I just gotta say one thing: PATIENCE!
Run Royal Jelly Palace/Sovereign Slime for a while, it's pretty fast and you can make an easy 2-3k, or more, depending on your luck, and 4* orbs have a tendency to drop. If you're already 4* equipped, then start running some T3 arcade in search of arenas and hone your skills and work on your survivability. Having people carry you through the game isn't really going to teach you anything, nor is it really fun. Why have people carry you through these missions when you can enjoy the game yourself? ;3
If you get bored with RJP, I might recommend Ironclaw Munitions Facility/Built to Destroy!, it's one of my personal favorites and while it's a bit slower, the payout is still pretty good and it breaks up the monotony of running the same mission so many times.