How many days total has it been since the 
auction ended?  You have to wait at least 7 
before even getting to file a NPB report, and 
then another 10 days after that before you can 
officially declare them a NPB (and get your fees 
back).  I think this is the time you 
really "should" wait before relisting.

If you really really want to avoid fees though 
and catch the free listing day, you might want 
to list the auction with NO buy-it-now for 7 or 
10 days, and if the first bidder comes through, 
then you can cancel the relisted auction.  The 
bidders, if any, will be annoyed though and you 
risk losing future business from them.  So it's 
up to you!