I have been plotting a bunch of planets using a universe I created in autocad. If it were back in the old days, I would have written a piece of software to do it, but I don't think I could manage "hello world" today.
I keep all the maps, so if I really need to I can plot the path of any planet pretty quick. The thing that I picked up is that the planets maintain movement along a specific radius, the centre point being somewhat random, but I can determine where any planet is going to be within a couple of light years on any turn, "except", for those planets that track off the edge of the map, because I haven't seen it happen yet. However, I think that they will just ride the edge of the map until they meet their track again. Have to wait and see.