Mortgage applications in the United States rose last week as more homeowners refinanced, according to the Mortgage Bankers Association. The MBA's index of applications to buy a home or refinance an existing loan increased 0.5 percent to 588.6 from 585.8 a week earlier. Refinancing rose 1.8 percent, the first gain in three weeks. The group's purchase index dropped 0.6 percent to 382.4, close to a