Yea there is many ways they can go about lex again like what they tried to do this past season with the injured lex, i thought nothing was overally wrong with that, yes it wasnt michael but they did the best they could with what they had. Now if they do want lex back they can go 3 ways in my mind, 1. say lex really did blow up in the truck and zatanna brings him back via black magic. 2. There is a clone with lex's mind but a different look(which happened in the comics if i am correct right?) or 3. Say the lex in the truck was a clone and real lex was montioring everything from a remote location and when he saw the clone get blown up he thought it was the perfect cover to stay hidden to the time is right to strike out again.