Do I need to pour any remaining resin in the vat back into the bottle after printing?

Generally, it’s okay to leave residual resin in the printer’s resin vat between prints, provided the next print is in the same resin and the period between prints isn’t too long. You’ll need to make sure to thoroughly stir the resin left in the resin vat before the next print to ensure the material is thoroughly incorporated, as resins are prone to separating over time. If you’re leaving it longer than a couple of days between prints, it’s recommended to decant the resin back into the bottle to limit the material’s exposure to dust and other contaminants. When pouring the resin back into the bottle you’ll need to pass it through a filter to remove any particulates suspended in the resin.