This is exactly the problem that SpaceX (And Blue Origin eventually) are trying to solve with re-usability. Think of a SpaceX launch, the "big" part of the rocket is thrown away just minutes into the flight, once it's fuel is expended. There's really no way to shortcut that, you couldn't refuel that part in-flight. Refueling that part after it lands again is much less expensive than building a new one entirely.

Meanwhile the payload on the top is now "in orbit" but operating in a vastly different environment than the larger component, with different engineering constraints, quite likely using different types of fuel.

If you could couple the initial launch vehicle being "cheap and easy" with another system for moving around to different orbits or getting into even higher orbits (https://en.wikipedia.org/wiki/Skyhook_%28structure%29 or a "space tug" type orbital vehicle) now you have access to high-orbit/cislunar space, and you can start assembling your larger inter-planetary vehicles or space stations there. (Perhaps using a mass driver to move heavy but necessary things like water and other raw materials to the site at this point, but that greatly depends on what the cost-per-pound of launch can get down to, and what resources you can scrape up out of the solar system)