Hi London2016,
First off, a 720/Q48 is an OUTSTANDING score (it's above the 90th percentile overall), so you should apply to any Business Schools that interest you. As such, a retest is likely not necessary. You've mentioned some highly competitive Schools, so you have to make sure that you have a strong OVERALL profile AND that you 'market yourself' correctly to each individual School. As such, you would likely find it beneficial to speak with an Admissions Expert about your overall profile. There's a Forum full of them here:
ask-admission-consultants-124/We also have a go-to Admissions Expert who we recommend for the types of Schools that you're planning to apply to. If you're interested in setting up a free consultation, then we can help to arrange that for you.
Congrats again on your success!
Another GMAT Assassin has been made!
Rich