Question: I need a word to describe a review that has been made on a review.

The review itself I will call a "review", but if someone reviews the reviews, what can I call this? I can't call it a review as well as that would be confusing.

I need a short understandable word for it. Any ideas?

Answer: 
A review of a review is still just a *review*. 

You might risk calling it a *meta-review*, but understand that you would thereby put yourself at some small risk of being misunderstood.
Try to write it so that it is clear at any time which review is being referred to, and/or introduce your own terminology, e.g.:

1. for the original review:  

a. original review  

b. source review  

c. 'review being reviewed'  

d. Fred Smith's review (where *Fred Smith* is replaced by the original reviewer's name)
2. for your review:  

a. second review  

b. 'review-of-review'  

c. my review (where *my* refers to you)

You need to be inventive here.