"Processing fee" to get new person on lease

Here's the situation: my roommate is moving out, and my boyfriend is moving in. My roommate and I had a 12-month lease, and then we negotiated for a month-to-month after that. My roommate will give 60 days notice before she moves out at the end of March. My boyfriend will then move in. I was told by the broker agency that in addition to me having to re-apply for the apartment (along with my boyfriend applying, which makes sense to me), and us each paying for a credit check (which I paid for last year), we will also need to pay a $500 "processing fee." I did pay a large broker's fee when I moved in last year. Do we have any room to negotiate this? The $500 seems insane.