First of all, I am not familiar with running scripts in JMP. I am willing to learn though but will require some other training.
For these graphs, the limits for each particular dataset will not change. I will do this fairly frequently and there will be multiple columns of data with each column having different limits. The dataset has at least a few hundred columns of data but I only need to graph maybe 20 of the columns. Only these 20 columns would therefore need spec limits (reference lines) added to the graphs.