I disappeared for several months, sorry to be late on the replies, and thanks so much for your insight everyone!
I took the lily out of the pot and noticed that that roots stopped growing at exactly the point where I put in the new soil a year ago when I last repotted it! Something about the new soil seems to have pissed off the plant and it refused to grow into the new soil.
I divided and repotted it once more, and kept with the original soil mixture that it was doing well in for so long. (Standard well-draining potting soil with some pearlite) I think the soil it didn't like was too dense and I didn't mix it well enough with the original soil either. It's been about 4 months now since the re-pot. New leaves come in, then after they are about 4-5 inches long, the leaf tips dry up one by one until the entire leaf finally dries.
Could this be a disease of some sort? I'm worried it is sick beyond repair. Close to giving up
