Yes. The condensed milk is added here because it's part of the Thai tea flavour profile; but if you're not using dairy, you can just add granulated sugar, honey, maple syrup, corn syrup or another sweetener of your choice. You'll have to experiment with the amount though as I'm not sure how much table sugar would be the equivalent of 1 can of condensed milk. This can easily be done by adding and tasting until it tastes sweet enough for you. I would start with ¾ cup of sugar and add more from there. Note: If you are using artificial sweeteners, it may not help keep the ice cream soft and creamy like natural sugars would.