The issue of genetic degration has come my way a few times and my only response is my experiences.
I've been cloning my Reclining Buddha since 2001 with no loss to potency or vigor. I also had a pheno of Skywalker I cloned for almost 7 years. At times I had "Moms", one living over 3 years hydroponically, but the majority of the time I clone my clones as well. As most of us, I frequently start new seeds and always put the new strain head to head against Buddha to determine what the most viable strain for my production preferences is. I'm still growing Buddha.
Only a few strains out of the many failures I've had, did I attribute genetic weakness to the problem. Of course there were plenty generally genetically weak phenos that I started and eliminated, however, there were also some interesting plants that simply quite on me.
I grew DJ Shorts Blueberry for example, she continued to provide me with lesser quality clones every cycle until finally she simply fizzled out. I also had an incredible Bubble Chem slowly become a uni-foliate and eventually loose it's productivity. Both these plants reacted this way while the rest of the garden thrived as usual. Both, at one time, provided rich, quality harvests.
So I suppose my long winded point here is that chances are it is fine and I'd continue the effort if you enjoy growing the strain. IMO it's a rare thing to loose genetic vigor. It simply has not happened to me frequently.....
good luck and I hope her vigor returns!