For Great Wall tours (from 1 to 12 days), your deposit is fully refundable up to 30 days before your trip begins - provided you've booked 30 days or more before your final payment due date. Between 30 and 15 days before your departure, 50% of your deposit is refundable. Between 15 and 7 days, 25% is refundable. Shorter than 7 days, 0% is refundable.
For China tours other than the tours to the Great Wall, your deposit (except for the portion that has been used to secure/purchase the flight tickets or train tickets) is fully refundable up to 45 days before your trip begins - provided you've booked 45 days or more before your final payment due date. Between 45 and 30 days before your departure, 50% of your deposit is refundable. Between 29 and 14 days, 25% is refundable. Shorter than 14 days, zero is refundable. The flight tickets or train tickets may also be refunded depending on the cancellation policy or penalty the airlines and train operators issue for specific bookings.
However, if you wish to change your date, you can keep your deposit and reschedule for a future date. You may keep it for up to 5 years.