Currently there is no option to start the game from the very beginning. However you can recolor your completed pictures the following way:
1. Open the picture you would like to recolor
2. Tap Restart 🔄
3. Confirm you want to recolor the picture
Now you can color the picture again!
1. Open the picture you would like to recolor
2. Tap Restart 🔄
3. Confirm you want to recolor the picture
Now you can color the picture again!
Besides if the app is reinstalled your achievements and imported pictures will be reset.