I would like to know the specific purpose for SRAM having a bit line and a negated bit line? I might think that is due to stability reasons, but I would like to know more details about its specific purpose. Additionally, once we read the value in the SRAM, is this value lost or can it be replaced with another bit after another clock cycle?
You didn't specifiy which SRAM part you're talking about, so in general terms...
1) Complementary outputs reduce electromagnetic interference because the EM field outside of the pair is DC. In order to work properly the two signals should be routed close to each other and sampled with a comparator if your input is single-ended.
2) SRAM stands for Static RAM so the value isn't lost and could be replaced immediately afterwards. SDRAM is completely different Synchronous Dynamic RAM where the value decays over time and needs refreshing.