I'm unsure of the protocol to follow here, do I just keep providing hints? I feel like I'm reaching the threshold before I just give it away. Since this is a puzzling site, it seems like I shouldn't answer it at all and just leave it up until someone figures it out eventually.
I see your riddle has now been solved, but I'll post an answer anyway for the eyes of others who wonder the same thing as you did.
First of all, give it time. People are still looking at your riddle even if they don't all post up answers. Eventually someone will probably surprise you and solve it. This question lasted three weeks before being solved!
If you feel it isn't receiving enough attention, you can offer a bounty. There's never more than a few open bounties on this site, and that will guarantee more people trying to solve it. Offer 'em a cookie and the mugs will do what you want is the motto of the SE rep system. The hope of more Imaginary Internet Points will draw people to do all sorts of things!
If all else fails, then yes, keep on offering hints. In this excellent question, the OP kept on adding increasingly more obvious hints, in desperation at the increasing number of DVs he was getting, until he made it almost obvious and someone cracked it.
As a very last resort, if none of your hints and bounties have worked over an extended period, you might consider self-answering. It'd be better for you to post the answer yourself than for the puzzle to remain unanswered forever. But far better than that - more satisfying both for you and the solver - would be for someone else to find the answer, so you should post a lot of hints and wait a long time before taking the final option and self-answering.
This is a slightly modified form of my answer to a very similar question
This will vary from person to person. But, if solvers aren't able or interested enough to solve a puzzle, here's the process I would take (and that I have seen other people take). The order here is not exact -- in particular, the middle three steps could be rearranged. (For instance, if a solution was very close I'd give a bounty before hints.) But generally, these are the options I'd consider, in roughly the order I'd take them.
- Transcribe things. Get any tedious parts of the puzzle out of the way. Make your puzzle as accessible as possible. If you have an image or audio file, convert as much of it as possible to text -- if all the solvable pieces can be transcribed, that's even better (and you should make a note of that!). (This should probably be done anyway, but if you haven't done it yet you should do it here.)
- Confirm progress. If any partial answers have been posted, tell them what parts were on the right track. This gives solvers something to focus on, and perhaps they can use this information to see why other parts of their partial solution were incorrect. (Note that some solving may be done in The Sphinx's Lair or in other site chatrooms, so you should read there to see progress too! No point in giving hints for things that people have already figured out.)
- Give hints. Hint as much of the puzzle as possible without giving a major "aha moment" away. Start vague, and become more specific over time. Edit these hints into the question, and perhaps notify people who were interested in the puzzle before. (This may give them motivation to finish the puzzle.) You might also want to edit the puzzle to clarify parts that you see people getting stuck on.
- Start a bounty. This can draw people to take another look at the puzzle, but won't always work. Make the bounty proportional to the amount of progress left - a 50-rep bounty will be fine if it's a small puzzle, but a larger one might be needed for a larger puzzle (or one with more work to do).
- Self-answer. Explain the intended solution path. Add comments on what worked and what didn't, where people got stuck, and what you'd do if you were to remake the puzzle.