How can I preserve yogurt for at least 2 weeks without preservatives?
Stored in the refrigerator, homemade yogurt can keep for up to 2 weeks. If you're planning to use it for re-culturing a new batch, you'd want to do that within about a week. You can also put active yogurt in the freezer to save it to culture future batches.  For this, one trick is to freeze in small amounts of about a tablespoon each using an ice cube tray (I use a ravioli mold).