excel：包含未知数据的图表

Let's (for discussion purposes) say that I have x and y data in 2 columns. They're some measured data which, several times a day, a few of them are added (usually 4 times a day). Now, I wish to plot y=f(x) (linear scale), but the problem is since data is constantly added to determine the number of points which will go in the plot. Always creating a new plot and then formatting it and all, is troublesome for ... reasons.Let's (for discussion purposes) say that I have