I was planning on writing about volunteer work at a local animal shelter, but this is something that I included in my application. Would this be too redundant or would it be okay? I already wrote the essay and my english teacher says it is very good.
I think you should write a different topic 
If the work at the animal shelter is very important to you and reflects on what you are as a person, it should be OK. You could check with your English teacher who knows you and read your essay.