Layer soy milk, flour, oats, and maple syrup in a blender. Blend on medium speed for 2 minutes. Pour batter into a bowl or 4-cup measuring cup. Thin with more soy milk if needed.
Heat a crepe pan or nonstick skillet over medium heat. Pour in 2 to 3 tablespoons of batter and tilt skillet in a circular motion to coat the bottom. Cook until edges start to curl up, 4 to 5 minutes. Flip and cook until second side is set, 3 to 4 minutes.