I have extended my stay in china but previous Visa of double entry got cancelled .

Hello, i came to China with double entry (No. of entry-2) ,M type. As per rule after 30 days i filed for stay extension and duly received the extension but for 60 days.However they have cancelled my previous M type of double entry.The new one shows "No of entry-0".So after 60 days is it possible to extend further and Secondly if i go back to India do i need to apply for new visa ?