Tubular wheels and tires are the ultimate upgrade for cyclocross - but if you're sticking with clincher tires and inner tubes, you can still get some similar performance benefits by using high-quality latex inner tubes. Latex tubes are more supple than traditional butyl rubber tubes, and often offer weight savings - making them ideal for race day.
Latex tubes do not retain air as long as butyl rubber tubes. This does not mean that you have a puncture, however. You'll need to add air before each ride (you'll want to do that for every cyclocross race anyway.)