Also during kata if the judges cannot determine who is doing something wrong they may ask you to repeat a certain kata.
For my nidan shinsa (test for 2-dan) my partner missed the suriage on gohon-me (5th kata). We were asked to repeat gohon-me and I later asked a sensei on the testing panel why.
He told me they wanted to determine if he missed the suriage because I wasn't swinging straight or if it was because he wasn't doing the technique correctly. (It turned out he missed the suriage both times due to incorrect technique).
Kendo-Guide.Com: Thanks for adding the info. It is true that the testing panel will ask you to re-do what they want to see again.