You don't need to pay cash for the rest of the year. Just pay cash for a set of pills and don't run it through your insurance. Then you keep running it through your insurance every 28 days. When you pay cash and don't run it through your insurance it doesn't reset the clock, so you can keep going every 28 days for your insurance refill. At most you would need to pay cash a few times a year.
Insurance is complex, and I could spend a lot of time running down the system. But the key for right now is to work with whatever system you have to make it best for you. It might be changing your prescription as some have mentioned, it might be getting an exception (which is probably possible), it might mean doubling the dose and then cutting them in half, there are a ton of ways to work the system... For me it is paying for a whole year of my thyroid medication at one time. I get it cheaper than the cost would be if I ran it through my insurance and had them pay every three months for a three month set. And I get the huge benefit of having a year supply and not having to get refills all the time. But I do need to pay cash and I do run the risk of the dose changing while I have months left. But just like politics, we get the system we deserve. People abuse health care insurance by running up bills without good reason (encouraged by health care providers) and then complain about the cost. Insurance companies have no choice but to figure out how to cut costs somehow, hard to blame them for that...
When I go to many other countries to provide health care I am amazed at the hoops they need to jump through, they are different, but there always seems to be hoops and expenses somewhere. Nobody has the perfect system, not America and not anyplace else. Just a matter of working with the system you have.