I have tried reattaching them and not been successful. I have used 3M 77 adhesive which was recommended and worked ok. The problem comes in that you have to clean the surfaces (both the mat and the floorboard mounting spot) really well for it to work. (The floorboards can be cleaned spotless but the mats are next to impossible to clean properly.) And even then, it never really stayed attached around the edges and it picked up all kinds of dirt and small pebbles.
It is also really messy and hard to keep in only the spots it needs to be. Then if you ever have to remove the floorboards for maintenance, the mats have to come off to access the top of the screws and you have to start all over reattaching the mats. Maybe silicone would work just fine. I would rather have some kind of velcro attachment so they could be easily removed and then reattached. Mine are currently off as I consider options...