144 days visa even though I have been in China?

Hello! I am in China (Shanghai) now for studying one semester with a x2. They told us at school that we can apply for one more entry, which we will do sa that we can travel to Tokyo. But we can't apply for more..
The problem is that I also want to travel to Bali.. Is it possible for me to use my entry to visit Tokyo and then like a month after leave China for Bali, and then come back (I just need to stay for like three days to do my finals) before going back to Sweden. Would this be possible without a new entry permit? If I just stay for three days?

Thank you in advance!