Assuming you have the existing plot in Origin. There are a couple things you can try.

1) You could add a second layer to the plot, to show your new data points. Then, you could fit a line (or curve) with Confidence Intervals and see how it compares to the existing graph.

2) You could fit a line (or curve) to both the new data and the existing graph, and then use Compare Datasets to get some descriptive statistics