Most extract batches can make multiple runs of extract. Lets revisit the basic vanilla recipe. Three vanilla beans in twelve ounces of alcohol. Let it sit for four-eight months or until the alcohol turns a nice dark brown.
Step 1: Now at this point, before using your extract, decanter the top four ounces ( one third of your total amount of liquid) off the top of the bottle.
Step 2: Start using that four ounces you decanterd off the top of the bottle.
Step 3: Refill that top third you just took off the top with new alcohol.
Step 4: Let sit for six to eight weeks. After that time the top four ounces will have changed into more extract
Step 5: Repeat steps one through four for multiple batches of extract.
Step 6: Every twelve months add a new vanilla bean to your extract.
Step 7: Enjoy Vanilla Extract for the rest of your life!