How do I prevent my dogs bed from sliding in her kennel?

I would suggest that you line the kennel under the bed with a flat piece non-slip carpet rubber mesh. This is what is recommended to hold area rugs in place on wooden flooring. I have seen it for sale both in packages and in rolls. Yes, it is easily washed with regular soap and water.

You could use Velcro to hold the dog bed in place. They have peel and stick Velcro that would work for this.

You could use double sided carpet tape. Just be aware that the adhesive on the carpet tape is incredibly strong and will be very hard to get it off the floor. We used it on our tile once and solvents, scrubbing and scraping finally we got it off. AHH. It definitely works!!!

Attach hook and loop to the bottom of the cage and to the bedding on each corner. Second option, attach cording in each corner and tie to the corners of the kennel. I would go for the velcro type on the bottom so she cannot chew on the strings.

You need to permanently attach a piece of outdoor carpet to the bottom that can be hosed off if need be. Then put a soft bed on that they can scratch and wad

up to their satisfaction. It's their nature to " make a nest" for their bed.

You could anchor the bed with velcro which would prevent it from moving around but allow you to remove and clean.