If you are on a prolonged trip, it is not necessary to pack a different piece of clothing for each day. You can use a local laundry mat or have the hotel wash some clothes for you.
Some hotels actually have laundry facilities either on each floor or in the basement somewhere. Also depending on your status with that hotel, the laundry services may be complimentary.
Take a walk down the street and scope out your neighborhood. You can get soap at a machine at the laundry mat and save yourself some weight of dragging stuff around with you on your trip.