Cessna cowl lamps are well know to have a very short life, the only way to increase that is to modify (via a 337) to a better quality bulb. Usually automotive motorcycle bulb.
My Cessna has wing mounted landing/taxi lights and they lasted 5 years and 3 years. My hangar mate used to blow GE 4509 and Q4509 bulbs every 10 hours; 7 years ago he changed to the automotive style via a CAA 337 approval. He has not change a single landing/taxi bulb since then!