I use Buy It Now a lot on ebay for 30 days and like everyone else, I normally have to keep recycling those items every 30 days because they didn't sell..
Like you I relist an unsold item after 30 days. Sometimes it will sell the second time around, sometimes not. Next step is lowering the price and still putting in on buy it now for 30 days. The eventually sell if the price gets low enough or if the right person comes along.
Case in point:
I had a piece of electronic test equipment so obscure there were none of that brand on ebay.
Didn't sell on a 7 day. Didn't sell on first 30 day. I had it at $300 or best offer (I would have taken $100...I paid $20).
Second 30 days listing..same price, still would have taken $100. Lo and behold a guy offers $100 and sometimes I figure..."he'll probably go more, maybe $125" and I counteroffered with $150 thinking he would come back at $125. He comes back at $150....naturally I took it and ran...he paid within a couple of hours.