I can think of a couple of ideas:
#1)
Create a bevy of Dwarf Maidens sacrificed to keep your dwarf lich/lord company as undead consorts throughout eternity. Over the Aeons he's forgotten about them, of course, and they've been left to haunt a disused wing of his lair.
The strain of being undead for many long years has driven them all insane, bitter and hateful of living things. You could even throw in an elven banshee who he killed and turned into an undead servant out of amusement. If the PCs kill and release the souls of these undead, they might be able to help them with a couple of clues about their foe's history and/or weaknesses (they were once good, and hate him for enslaving them).
#2)
A twisted and evil Dwarven cleric/aristocrat who serves as his eyes and ears in the court of the current reigning dwarven lord. Nobody suspects that this wizened advisor is actually a servant of the evil lich lord. Kind of like Grima Wormtongue from the Two Towers, only short and with a beard.
#3)
An automaton of a grizzled dwarven veteran. He should be majorly skilled at melee combat. The lich can inhabit this automaton as an "alter ego" to allow him to travel through the outside world. Only a learned sage could recognize this creature as a "clone" of the lich, as the physical form resembles the lich ages ago when he was still alive. The concept here is similar to the "Kananga & Mr. Big" relationship in the Bond movie Live & Let Die, where the villain Kananga disguises himself as his own henchman, Mr. Big to divert attention from his nefarious plot to control the world's drug trade.