Hi Rohit,
If you feel you can perform better on the GRE, and you have the time etc to invest, then I would say go for it and see how you do. It's ok if you've had the scores automatically sent to schools... it's basically just digitally filed away until if/when needed, but you indicate your scores on the application and schools can assess in the instance of the GRE being higher. Either way I strongly recommend you invest in good preparation if at all possible... suggested companies for prep would be Manhattan GMAT or Kaplan; either a tutor, course, online course.... and either way include multiple full length, realistic computerized tests. Good luck to you!!