I don't know about getting weak but you are talking about a very old plant. Maybe we are just talking old ? Your clones are the same age as the original seed it came from and if you don't know how long it was cloned before you had it then 3+ years. That's old dude. About 2 years me and my bro start running into prob's. Clones get deformed and don't respond good to what it did a year before.

Time for fresh and then you can tell if it's the plants or you. lol