Conversion of Single entry X2 type to X2 type Multiple or Double Entry Visa

I will be going to Shanghai for their Spring semester exchange which will only last for 4 months and hence i was told to apply for X2 type.

However, the China Embassy in Singapore only grants Single Entry X2 type which was prior knowledge to me before i booked my flight and accommodation to Japan during the holiday in the semester.

I am now really very worried that I will have to cancel the entire trip.

Has anyone with such experience before and can share about how you guys applied for Double or Multiple entry X2 type?

Thanks a million!!