There is a widespread misconception among test takers that because your reading level is difficult to improve (taking years to develop), your performance on the Reading Comprehension passages is also unlikely to change. This belief reflects a common misunderstanding about the specific type of difficulty associated with reading comprehension passages. Keep in mind that the test makers generally have about a half of a page to get their points across. LSAT authors are limited to the degree of depth that can be reached within this context. This is not to say that these passages are simple, but that the challenge often comes from sources other than conceptual complexity.
The LSAT is not only a test of conceptual abilities—but also, in large part, a test of intimidation. So, how do the test makers ensure that the passages are challenging? Often by choosing subjects that seem daunting. Many passages are based on esoteric topics, filled with sophisticated-sounding scientific or technical terms. It is vital that you avoid intimidation as a response to words or phrases which you have never seen. The makers of the LSAT do not expect or require outside knowledge with regard to Reading Comprehension passage topics. Unfamiliar terms or phrases are almost always either defined outright or surrounded by context clues. It is important to understand that unfamiliar words or phrases do not necessarily make a passage any more conceptually difficult. What matters is your ability to react properly when confronted with novel terms or phrases.
You can find more LSAT Reading Comprehension tips and guidance in the LSAT Reading Comprehension Bible.