Hi hauyuuu,
First off, your original 680/Q49 is a strong Score, so it could be enough to get you into your first-choice School. As such, another retest might not be necessary. You're ultimately asking Admissions questions though, so 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/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 (or gain) there. In addition, most Programs are fine as long as your AWA is a 4.0 or higher. If you would like to know more about how an individual School or Program views these two aspects of the GMAT Score, then you should reach out directly and ask (and most Schools would be happy to answer any application/admissions questions that you have). As an aside, are you sure about how your 2nd set of Scores? I ask because the highest possible IR Score is an 8 (not a 9).
GMAT assassins aren't born, they're made,
Rich