Use the non-dominant hand.
利き手じゃない方の手を使おう。
When you feel uninspired, draw something with the non-dominant hand. It’s an enjoyable experience and probably the best way to draw like a child. It also stimulates your brain and is, in fact, effective for improving your brain function.
Keep doing this for a while, say 10 minutes. It can give you a source of great inspiration. At least you no longer feel mundane.