How do I fix the plastic shields that are falling off underneath my Chevrolet Prizm (Corolla)?

Underneath the front of my Chevrolet Prizm / Toyota Corolla (they are the same) there are some plastic panels / baffles / shields that protect stones, dirt, etc. from going up and hitting the radiator and engine. However, many of the screws holding on the baffles have rusted and broken off, causing the shields to dangle down. I am not sure what I can do to fix this - Do I somehow drill out the old screws? Do I bore new holes and somehow bolt them through?|||find the pre-existing holes the plastic shields were held on in the first place and use zip-ties. the wont rust out and if you ever need to take the shields down, you can just cut them.