Yes. There is a window on the west side of the south west room in Elrath's house, which you can throw a teleporter pyramid through. It is at the northern corner; there is a window on the east wall and a couple small ones on the south, but I was not able to get a teleporter stone through them. In detail:https://www.dropbox.com/s/qu58mi1scrym6qz/elrathbreakin.jpg?dl=0
Alternately (probably not as easy), you can get back in the basement either by hex editing (Teleporting Anywhere
) or file swapping (FIX for the Missing Catacombs Portal
), or replace the set of potions (Lost Items - guide and directory of inventory files
By design there are only 2 cure potions in the game, but 3 victims. There are ways around that, though.
You can Pickpocket (level 2) a potion back from a cured person, kill one after curing (with no loss of reputation) to get them to drop the potion, or duplicate the potions before using either.
To copy a stackable item, drag a stack out of (or into) your inventory (or container) and hold down the control key before dropping. This will bring up the split stack pane; type in a negative number and hit enter (the checkmark will be greyed out). This can also be done in the trade window.