Find a new image in an old painting by cropping, using a different medium, changing the colour etc.
Sometimes scaling up a small area of a piece of work can be more successful than the whole image.

You will need to bring a couple of previous paintings, 2 L-shaped pieces of paper or card to form an adjustable "frame", plus the materials you want to use for your new painting.

Alternatively bring something that you are working on and you could continue with that.