Short answer: yes! As sugar replacements are often very different in weight and volume, however, I've found it best to measure it by volume and add 1/3 cup of the sugar replacement to replace the 1/3 cup of brown sugar. Depending on the type and brand you use, the conversion might be slightly different, however, so I recommend checking the packaging instructions to see how to most accurately convert the amount. I've tried this recipe with Splenda, measured by volume, and it's worked out perfectly fine.