Replacement is still possible (I used to work in a shop that did the same) but definitely way out of the reach of users. If I recall correctly, you have to order replacement adhesive from Apple, and when I was working there third-parties hasn't come out with their own replacement adhesive yet (Apple will not sell any sort of parts to users).

You can buy self adhesive strips on eBay, I upgraded a 21.5" machine last year.