Programming is fun, and interesting. Improving on what you know is also usually fun, and interesting. So take some time, and do it. Be the smartest person in the room, and then move onto the next room, or something.
Regularly drilling yourself on core competencies is a good way to stay prepared, and identify your own places for improvement. You need to be competent with core data structures, and algorithms to succeed in an interview. You also need to be able to identify where to apply such algorithms when presented with coding problems.