I completed the template a couple of months ago. I had the same problem and had to take it down even more. I did unweighted p/u's and unweighted L-p/u's until I had worked up to the prescribed sets and reps.
I asked pretty much the same question and to sum up the response it was do the weight you can and increase it as you go but try to get all the sets and reps in.
Best of luck and let us know how the progress is going. Are you keeping a training log here on the forum, if not you should for the motivation.
What we think, or what we know, or what we believe, is in the end, of little consequence. The only thing of consequence is what we do. -John Ruskin