My sister just received B2 visa in Chengdu after she was denied first time a couple of days ago. I am posting this to encourage you not to give up easily. If you are persistent enough, you will get what you want!
I am getting married in March so I invited my parents and only sister to join my wedding. My parents visited me last September and went back to China after two months. Therefore, they got the visa quite easily. However, my sister never traveled oversea and I just switched my status from F1 to H1. Therefore, she was rejected on the first round.
I was very disappointed and didn't want to just give up cause I would really want my sister to be part of my wedding. Therefore, my fiance, my sister, and I all emailed and faxed the consulate letters to state the reasons why we think her application should be reconsidered. Further, my fiance called the embassay. After yelling at 5 people, he got to talk to a head supervisor there and discussed the situation with him. The supervisor was vey nice (like what always happens. The supervisors are generally nicer than the staff.) Anyway, he said there is no process of reconsideration. But we could reapply through another consulate and he also would post our information in their office.....So people work there would sort of familiar with our case.
When my sister went back the next week, the staff who collected the information there recognized my name:)! After showing the docs to the consulate, She got the visa....
I am so happy that my parents and sister will visit me soon! So don't give up!