@virgofq
As you already pointed out, a band score of 6 in Listening meets the (anticipated) threshold of CLB7. The next level CLB8 requires a 7.5 in Listening - a steep increase from 6. I think it is unlikely that the minimum threshold will get reset from CLB7 to CLB8 (of course, this is my personal opinion). So, in all likelihood, you should be safe.
The other factor to consider is - with your current IELTS scores, you're scoring 22 points out of 24. If you are short of the 67 points and need to improve on the language score, then consider re-taking the IELTS test. If not, you are probably better off with a status quo. If you decide to retake the test, keep in mind that there is a danger of your score going down. Good luck either way!
-Ganman