Dear Nomair,
Sometimes we are focusing on the subjects like English, Science and Mathematics as they seem to be difficult. Consequently other subjects are rather ignored. In order to improve in Urdu you need to prioritize this subject. Try to go through any Urdu newspaper daily, read Urdu story books of renowned writers and read articles at vshine.com Urdu version and try to contribute for the magazine. You will get a lot of vocabulary, structures and expressions of Urdu language that will enrich your Urdu skills and hence you will have a good command over this language.