Heat up milk on medium heat in a large saucepan to 180°. Stir consistently to make sure the milk does not burn on the bottom on the pot.
Once the milk reaches 180°, allow the milk to cool down to 110°.
Measure out kefir and thin it out by slowly adding milk into the kefir.
Add this mixture into the milk and mix well.
Transfer the milk mixture into clean and sanitized glass jars.
Incubate the jars in a large pot or pressure cooker that has water that is heated to 110° for 8 hours.
After 8 hours, put jars in refrigerator and enjoy!