It doesn't seem like a software issue to me, so I'd guess no fix will come aside from LTE coverage improving in your area.
It's just the cold hard facts of where the state of cellular radio technology is today. It's pretty amazing as is that the iPhone 5 can be so much thinner, lighter, support a larger hi-res screen, be twice as fast, and support LTE. The spotty LTE issue is just one of those compromises that I don't think much can be done about.