I don't know if tire pressure sensors can or need be "rebuilt". If they completely fail, my understanding is the sole remedy is replacement. Usually, the "failure" is leakage, which is caused by a single rubber circular gasket deteriorating. This little gasket wraps around the valve stem at the interior of the tire. The seal is held by the nut at the exterior base of the valve stem. You have to dismount the tire to access the seal.
Many tire dealers have TPS seal "kits" in stock. My dealer replaced a seal for $17. My gasket seal had become "crushed" probably from my overtightening the exterior nut. My guess is that so long as these gaskets are properly torqued they will last almost indefinitely.
Many tire dealers routinely replace valve stems on conventional tires when replacing tires. In my opinion this is usually unnecessary; and so is replacing the gasket on TSPs.