Have you ever tried keeping on mock test practice a period of time like 3 months before the test? An intensive practice and learning may in effect help you improve to a large degree when it comes to sitting a formal test. I did in my IELTs and it helped me reach a level enabling me to pass the minimal requirement for the graduate school.

However, a long term investment in language learning may require you to be immersed to a Chinese speaking environment. That is a long term plan.

你好！我赞同上一位的评论，如果想提升中文水平，就需要为自己营造一个语言环境，而且其实任何一种语言的学习都是这样的。你有从前学习中文的经历，多听多说，就一定会有进步。你更可以找native speaker，并大胆地与他/她使用中文交流，这样你的口语水平会有很大的提升。

如果一时没有太大效果，也不要灰心。坚持下去，你一定可以看到好的结果的。加油！😊

如果有什么不太明白的地方，可以来找我哦！谢谢！😜

I have done a rough research about this. See this(a bit old though): https://www.reddit.com/r/ChineseLanguage/comments/2cn840/tips_for_taking_the_actfl_oral_proficiency/

Apparently, it needs a good vocabulary level about daily life of China in details, the knowledge about what to say in different situations, and making it easy to be understood, as it is based on interactions.

I don't have the experience of this test, as I am a native speaker. But I have the second highest level of certificate of Mandarin Proficiency Test, which makes it enables me to be a broadcaster or a Chinese teacher in the middle school. I am proud of my standard accent.

I can offer some help if you need in detailed vocabulary and simulations, when I have some time free. But as I am in Paris, there will be time difference.

嗨！您好～我來自台灣