Hi ChinmoyAdhikari,
First off, a 760/Q51 is an outstanding Score, so you can comfortably apply to ANY Business Schools that interest you. As such, a retest might not be necessary. Since many Business Schools have publicly stated that they don't use the IR score as part of the application process, you likely have nothing to worry about there. In addition, most Programs do not put too much emphasis on the AWA/Essay Score (and they tend to be satisfied with an AWA of 4 or higher - which you have).
Assuming that you are planning to apply to some highly-competitive Schools, you would likely find it beneficial to speak with an Admissions Expert about your overall profile and plans. Those Experts should be able to answer your Admissions questions and help define the specific areas of your profile that could use some improvement. There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/GMAT assassins aren't born, they're made,
Rich