Need advice for getting through Language B

I started taking really hard subjects and i've slowly dropped all my hard HLs and picked up easier ones (changed Maths AAHL to Business SL for example). Now I'm getting a 7 in all my subjects except Japanese B SL where i'm getting a 4. I actually don't know what to do. I feel like no matter how hard I study my results never improve.

Any advice from others who took difficult B languages? How did you get through it?