It has been almost two weeks since I filled the reservoir, I have seen couple bubbles but still staying on the same level which is good.Two years? Needs changing.
Level it out, suck out the old fluid from the reservoir, replace with new DOT 4, bleed system, put it to the correct level, ensure the diaphragm and cover is sealing well, and keep an eye on it.
Look for signs of leakage at the slave cylinder.