If you haven't done it by now, now is not the time if your test is soon. By this time you should be polishing what you already have rather than trying to make major changes. That never goes real good in a test since you will be preoccupied with the speed of your kicks and what you have will not be solid. Much more chance to mess it up in a test.
You could put off your test for a year or so and work on your kicks with stretches and strength exercises and it will take about that long to see results. There is no 'fast' and 'I need it by tomorrow' in martial arts. All has to be earned over time.
"teasing"?
For a black belt test, there's nothing you can do to help much, if by "soon" you mean in the next couple of weeks. Your instructor has already deemed your kicks good enough for testing, so, I would focus less on improving them, and more on developing your stamina and practicing other aspects of your training.
This is time better spent on perfecting your forms and breaking. You should also do a lot of cardio exercises, like biking, swimming, treadmill, etc, since that will help with sparring stamina.
There is not enough time for you to increase sparring speed very much. I would focus on demonstrating the kicks correctly, your forms and your one steps. Unless they specifically told you that you are too slow in sparring, don't worry about speed. If anything, I would work on combinations to use during sparring.
I am teasing for my black belt pretty soon and I want to increase my speed for sparring. How can I do so?
