By ASHLEY M. HEHER Sears Holdings Corp. cut its second-quarter loss by more than half as profit margins perked up at its Kmart chain, the retailer said Thursday.For the three months that ended in late July, the owner of Sears and Kmart lost $39 million, or 35 cents per share. That's better than last year's loss of $94 million, or 79 cents per share last year.