For a basement ceiling, just the opposite. If there is insulation between the joists on the attic floor, and no vapor barrier, take out the old insulation, install new insulation with paper backing or install polyethylene plastic, then put back the old insulation or put in new, unbacked insulation. Where insulation is blown in old houses, there is no vapor barrier, and it is impossible to install one without tearing out the walls. You can do a lot in an old house, but you cannot tighten it up that much without taking it apart and rebuilding it. New houses, however, can be built so tight that you save a bundle in heating and air conditioning but pay the price by too much water vapor and other pollutants indoors.
Water vapor is a big hazard because it can condense inside the house into water, and mold can grow.
There are a couple of other ways to make a house tight, comfortable and cheap to heat. Windows can be a major heat loss. If your ancient windows are weatherstripped, relatively tight and with efficient storm windows, there is little need for new ones. But if you want new windows, consider replacing just the sash, the movable parts. In a double hung window, the sashes are the two pieces that slide up and down.