I got this idea after doing many a fuel run to my interplanetary vessel. with 8 large red tanks to refill i made a launch vehicle which transported approx 1.5 tanks into rendevous with the interplanetary vessel. because this took multiple launches of the same vessel it got a little tiresome. So i thought 'What If?' - have a tracking module that can be attached to craft, so once you have launched it and got into orbit, you can then right click the module and 'Save Launch peramiters' (orital periaps, apoaps, and fuel) . then from the space centre have an option for 'Repeat launch' that duplicates the ship in orbit with say 5-10% less fuel and and approximate (+/- 5%) orbit. im sure this would be a fairly simple mod, but i lack the skills to make it myself, but i feel it would be a very helpful addition.