Travel to China for 2nd time. Do we need to apply for the visa again?

Dear Sir,We are a Filipino family of six.....last 2009, we had secured a Chinese visa when we went to Shanghai for one week...this April 2012, we plan to go to Hongkong, Macau and Shenzen with our four kids ages 13, 11, 8 and 4......do we need to get chinese visa again?thanks!