In order to make kefir fizzy use the lid instead of a muslin cloth when it's fermenting.
Once you have given the jar a good shake with the lid on, leave the lid in place and allow the kefir to ferment for 12 - 24 hours.
This is applicable to all types of kefir - milk, juice, coconut water. However the results will differ depending on how much sugar is in the base you use, low sugar will give less fizz.