That is not necessarily the best approach, the current bill has yet to be signed into law by the President. So not sure if it goes into effect. Also, the law is not necessarily goes into retro effect, which means that today the fees are 100 $, you send in your application, tomorrow the fees increase to 200 $ does not mean you have to send in the difference. You applied under the original law so there is no penalty to you because the law changed. My suggestion is talk to a lawyer first. Or better yet call the INS and find out.
A gory example of the above is the Manson family murders. Which occured before the CA supreme court knocked down the death penalty in the 1970's. Due to which their death sentence was commuted to life in prision, but some time ago, the Supreme court reversed its stand on the death penalty, but it cannot sentence Charles Manson back to death row since his sentence is already commuted.
Let me know if the above was too gory for the board, I will edit this post.