kanna is dieing

[plantshaman]

been growing kanna in a pot for a few years now . it was doing good till this last year or so . It was in a small pot recieving 6 hours of direct light a day . Then last year new growth stopped and the lush green is now mostly brown and dieing . I tried some osmocote that didn't help . i tried more water and less water neither of those helped . I know the sun exposure is about right . I tried a new pot thats alot larger and that didn't help either . it used to bloom all the time and grow very well. Now it doesn't .... i think its on its last leg and if i don't do something soon it will die . Whats the problem ?!