Under the default setting, the maximal length of path is already long enough. If you want to decrease the maximal length, you should use less number of points.
PS: If the number of points is not adequately large to make a path reach a CP, then the path generation will be failed, and the path will not be shown.

I have change the parameter up to 5000 points, and the result seems to be the same

In the topology analysis module, there is an option "-2 Set path generating parameters", in which you can modify "1 Maximum number of points of a path". This parameter controls the maximal length of any kind of path.

No, I mean in a 3D plot with gradient lines of lap that go up to infinity

Do you mean you want to plot a plane map of Laplacian of electron density, in which the gradient lines emit from (3,-1) CP of Laplacian of electron density?

Could it be possible to draw the gradient paths of laplacian up to a distance from the CP (where usually ends up)