How to get crown to adhere to this? (Photo)

My first Crown snapped into almost 2 years ago, it was weak after having to have a root canal done to it shortly after placing in 2014. Apparently when my second crown was made it didnt fit quite right and the dentist shaved off too much of my tooth and it will not stay on. I have had it re-cemented about 15 times and the dentist wants me to just get an implant in there now. Can this be fixed, do i have other options. My front 6 teeth are all crowns also if that helps.