GPA is the most important factor for getting an IB interview. (and it's total GPA, not just business GPA)
Once you get the interview, raw intelligence and technical knowledge of finance is going to be the most important.
Unfortunately, your GPA is very, very low for IB.
Knowing Chinese is not going to give your resume much of a boost at all, unless you are applying for a position that actually requires Chinese knowledge (for example, a foreign position).
If your ultimate #1 goal is to break into IB, then your #1 priority is bringing up the GPA, and your #2 priority is having technical finance knowledge.
If dropping Chinese is what it takes to bring up the GPA, then so be it.
If you think you can get A's in Chinese in the future, then you can stick with it.
I personally think Chinese is a very useful language, but if you are 100% committed to being fluent, it is going to be useless since a Chinese businessman is going to have better English than your mere proficiency in Chinese.
I was also under the impression that language classes are a lot of work but that it's an easy A.