Sterilize the 1-gallon jar and any measuring cups you plan to use.
Brew half-strong tea for 2-5 minutes by combining 8 cups boiling water and 4 teaspoons loose leaf tea (or 4 tea bags).
Remove tea bags, straining cloth, and/or tea leaves.
While tea is still hot, stir in sugar using a clean metal spoon until dissolved.
Allow tea to cool completely to room temperature.
Pour cooled tea into the clean 1-gallon glass jar. Add SCOBY and the 1/2 cup prepared kombucha with cultures.
Cover with cheese cloth and a rubber band and place in a cool, dark place to ferment for 7-14 days, according to taste preference. Check daily for mold growth and to taste-test.
When the kombucha reaches your desired flavor profile, either pour into jars and refrigerate, or proceed to the second fermentation step. Reserve SCOBY and 1/2 cup of liquid from the bottom of the jar, which contains most of the culture strands to repeat this step for additional fermentation cycles.