Setting Limits on a real time XY graph

Hello, I have this XY graph with some real data. The limits were established prior to the WHITE lines have been drawn on the graph. That is leaving me with all kinds of FAILURE because of the existing test. Sometimes the motor is running too slow, grabbing too few of a data. Sometimes its too fast grabbing too much of data. Can I set the limits somehow were its more dynamic? As in, when the end slope is starting to ZERO out when where THE LIMIT line ends? Can someone guide me in the right direction. I am using Labview 7.0 I can open with Labview 8.0