Yes - more spackle! Seriously, once the wall has been painted, you are pretty much back to square one. You will need to lightly sand that area again, and then re-spackle. To help you avoid the same hassles next time, here are a couple tricks-of-the-trade that will help you check the wall repair before you begin painting.
First, the secret to a good spackling job is to use very thin coats and to apply them first with a small spackle blade (4 -6 inch blade), and then with larger blades to taper off the spackle into the surrounding drywall.
Secondly, when you THINK you are done and BEFORE applying any paint, grab a really strong flashlight and hold it against and parallel to the wall you just repaired to check the wall repair before you begin the painting process. As the light bounces over the repaired area, you'll be able to see exactly how this will look later, like when the sun hits it in that very uncomplimentary direction, revealing a pock-marked wall still needing work!