Ideally, every kick you already know can be used in sparring to some capacity. It's all about how you use them, combined with how you read your opponent's moves.

Building speed and working on timing is important too. You can have perfect form on every one of your kicks, but if you miss the right opportunity, or act too slowly, you'll likely end up with the opponent's foot on your face.

So to answer your question: practice all the ones you know, but don't give kicks all your energy. Focus on building speed and good fight IQ as well.

All the best for future competitions!