In sci.electronics.repair Arfa Daily wrote:
I just use the long leg on the new resistor or whatever to connect back to
the nearest undamaged point - either tracking that's still in place and
can be scraped back and soldered to, or the next genuine solder point up
the track.

On SMD boards I've used little slivers of RF shielding tape to make new
tracks. It's copper tape with adhesive on one side, you can choose whether
the adhesive is conductive or not. The adhesive is just enough to keep the
pad in place, and probably enough if the component isn't too big. You can
then solder it straight onto the component and an existing track (flux helps
here). The biggest difficulty is avoiding surface tension holding it to the
soldering iron and coming away when you remove the iron. (Using lead-based
solder tends to help here).

Theo