Start eating bread that has pottassium bromate as a preservative :-P.
Sorry I was just kidding.
On a serious note, I have read that Iodine get back to normal very fast so you should just back off the iodine.
There was a test I saw on a website.
They said take some liquid Iodine and apply it at 3 different place, just dab a fingertip size.
If the Iodine stain remains for long it means you body has enough iodine.
If it disappears soon that means you have less iodine.
So you could back of the iodine and use this method to check if your levels have reduced.
If you find a difference then take a test. Otherwise it would be waste of time and money to take regular iodine tests