Mortgage rates fell to the lowest level in a month, boosting refinance activity and offsetting weak demand from homebuyers. As a result, total mortgage application volume rose 1.8% last week compared with the previous week, according to the Mortgage Bankers Association's seasonally adjusted index. The average contract interest rate for 30-year fixed-rate mortgages with conforming loan balances, $832,750 or less, decreased to 6.42% from 6.51%, with points increasing to 0.62 from 0.61, including