Would it be possible to re-magnetize an implanted magnet that has weakened over time? Or would that require exposing them to very strong magnetic fields, which would rip them out of the body? (I've seen videos of magnet manufacturing, and when they exposed the new magnets to strong fields to magnetize them, they were always firmly clamped in place so they would remain stationary).
Yes you need high magnetic fields to re-magnetize a magnet. Seems like you need between 1 - 2T magnetic field to saturate a rare-Earth magnet. So it's not something easily achievable in a homemade setup.
