Scale scale scale. Unless you have scaled to the point you cannot scale anymore, just keep scaling.
Let me say that again. Scale, scale, scale!
Someone mentioned before about e commerce and there is always opportunity. Manufacturering your own product will be hard to scale and hard to get going (big costs too).
Selling other people products makes it easy especially online.
I am sure adsense is the same way.
Not to be rude but if you are asking this question, then you probably haven't made any money. If you have no idea what to do next, then how did you get to the place where you are now. Think about it?
Doing what you did to make the little money is the hardest.
Replication is the easy part
I am in no way rich whatsoever, but if I do what i have already done thousands of time, which I am going to, then i will be making big money. Set up the system, streamline the process and cut out the fat. It has nothing to do with online. If anything, online presents a much bigger opportunity to make "big money". Most likely you are thinking too small. Step up your game and start thinking bigger.