Hi there
There are already many threads here on bitcointalk which are explaining various methods to re-audit the twitter for free but they aren't working for most of the people. I have tried one method so far and used it many times on different accounts and it works perfectly every time. Follow the steps for a free re-audit(s)

1. Sign out/ Logout of twitteraudit.com. Close this tab.
2. Go to settings and privacy in your twitter account.
3. Go to Apps and find the 'Audit and Block Fake Followers'.
4. Click on Revoke access.

5. Now go to Settings --> Account and then change your username to some random name.

6. Open Incognito window and open twitteraudit.com
7. Login from a new twitter account there.
8. Type the new username of your old account in the search bar at the top and press 'Audit'.
9. It will audit your account as per current followers.
10. Now Login to your old account and change back to your original username.
11. Login in twitteraudit.com with your old account and you'll see updated stats there.

That's it!

It seems a long procedure but it hardly takes 2-3 minutes, all you need to have is a new twitter account. I hope this helps you and share it with your friends too and help them save some money.