At one year old he will not still be teething. This sounds like a habit he has developed maybe since he was teething as a five/six month old puppy. I would remove any bedding with stuffing in it, and replace it with vetbed, which is flat furry bedding with a canvas type backing, and it is quite difficult for them to chew up (but not impossible!). One manufacturer claims their Profleece bedding is non chew but I know some dogs who would eventually go through it.
Another thing you could do is to give him a plastic dog bed, and either put a flat mat or vetbed in it, or even some shredded paper although this can make a right mess - ok in kennels but indoors its a nightmare to keep in one place.
I am sure he will grow out of it in time, but till then don't spend a lot of money on expensive beds, support your local market trader pet stall and buy cheap and cheerful ones which can be replaced or even give him a large cardboard box lined with newspaper. Leave him with a big marrow or knuckle bone or pigs ears to chew on and I am sure he will gradually get out of the habit.