Add watermelon, 2 Tbsp granulated sugar and lemon juice to a blender and blend until well pureed. Skim off foam then carefully pour into 10 popsicles molds (I have this mold here if you are looking to buy one
) filling each about 2/3 full (try not to splash on sides, I found it worked best to let it run down the outside edge then just wipe off that part later with a damp paper towel or q-tip). Sprinkle the chocolate chips over tops then using a popsicles stick gently push down to immerse chips (push towards sides so you can see them once the freeze). Wipe sides clean as needed. Cover with the lid and insert popsicles sticks. Freeze 3 1/2 hours. During last 30 minutes of popsicles freezing, whisk together coconut milk with 1 1/2 Tbsp sugar until sugar has dissolved, chill 30 minutes (you want it to be a nice pourable consistency after chilling, not too thick. If you find that it is stir in 1 - 2 Tbsp cold water to thin. I recommend chilling it because you just don't want it warm or it will melt the watermelon layer when pouring in).