If it's a money league, you're playing a dangerous game kicking out owners that aren't "responsive." If you're not extraordinarily tactful about it, you could end up giving the impression that you don't mind taking money and then arbitrarily dismissing owners that you don't like. Not saying that's the case here. Just making sure you know the pitfall.
I had this problem in my league a few weeks ago, except the guy had paid. I still sent him a refund via PayPal and asked my new owner to pay for the entire year. I did that because, in addition to what I said above, if a new owner is truly dedicated and thinks that the team can win, he will be willing to pay up front.