The culture you have is a direct set culture. What you have accidentally done is make a mother culture. When you intentionally make a mother culture you let it ferment for one to two hours. Then you can then take this mother culture you have made and split it up in an ice cube tray or trays. Which are then stored in a freezer.
You can save the day by allowing the yoghurt, with all of the culture in, to ferment for an hour or two and then put this yoghurt mother into ice trays to freeze. Once frozen place the trays inside a freezer bag to prevent cross contamination and keep them in the freezer.
When making yoghurt you can use these ice cubes to start your batch of yoghurt.
If you can manage to find enough ice cube trays to make 50 yoghurt starter cubes, then each cube is enough to start 2 liters of yoghurt.