I’ve been painting a pixel character in a of 32×32, but after the work is almost done I noticed I needed a little more dots, Is there any way to edit the grid to something like 64×64?
If not, is there any way to copy the painted dots inside a bigger grid and paste in another rectangular grid?
You can create a new grid by selecting the Rectangular Grid Tool (a subset of the Line Segment Tool) and then clicking anywhere within the artboard. If you want to over lay this in the same spot as your prior grid you will click on the top left point. This will prompt you with a Rectangular Grid Tool Options tool box. you can then change the settings to be 64px x 64px or however large you choose.
After you’ve created the new grid you can make a duplicate of your original work and paste it on the new grid. To ensure pixel perfect accuracy you should consider having View → Snap To Point checked.