Can there be any way to repair cavities besides to drill and fill?

Yes. many options!: Cavities are actually a mixture of destroyed tooth structure, bacteria (& byproducts), and food that are in your teeth. The dentist removes the debris so that the remaining tooth or hole in your tooth is clean. This bacteria etc. Can be removed with a high speed drill, low speed drill, and even lasers. If the remaining hole is small then a filling (usually tooth colored) can be placed.

Potential Reversal : Depending on the extent of tooth destruction, various treatments can be used to restore teeth to proper form, function, and aesthetics, but there is no known method to regenerate large amounts of tooth structure. If the cavity is discovered at early onset a high Fluoride toothpaste, high ph rinse along with managing risk factors can be used to remineralization of very small cavity lesions.