She could choose to favor another race over them, one she found more evil, cruel, or spider like. If her favor was gone that would be the end of the matriachy's power but also engender a psychotic abandoned child reaction of "I will kill you to show you how worthy I am of your love and attention."
So in this scenario we have:
1) The Drow facing several set backs, siginificant enough to make them look weak in the eyes of the world.
2) Another evil race rising, perhaps by challanging the Drow supremcy of the underdark. A race that also honors a spider totem, but perhaps doesnt associate it with Lloth yet.
3) Lloth manifests to the other race demanding their worship and obedieance and in doing so angering the drow.
4) Drow high priestesses question Lloth's will. Drow High Priestesses die.
5) Weakend matriarchy falls in wide spread Civil War to rebellious male factions, perhaps united under a single strong male leader. Males, being more used to following orders, turn their society closer to lawful - say NE since their is still such a strong chaotic tendency.
6) Females continue to exert influence, but in more subtle ways, to turn the new male rulers into instruments of revenge against/tools to show their worth to Lloth. Perhaps during this time agents of other deities attempt to bring their patrons to the fore of drow life.
7) Male led army turns its attention to destroying Lloth's New Favored by first attacking and conscripting other underground civilizations to serve as front line troops or making common cause with other victimes of the LNFs, new NE outlook enables societal mechanisms to make both of these possible.
8) The Underdark goes to war, outcome as need.
9) Depending on results:
a. Drow win: Lloth accepts former priestess who were manipulating male leaders. Status quo returns for the most part.
b. Drow win and use Epic magics to assualt demon web pits, possibly with allies drawn from good races, and destroy or imprison Lloth.
c. Winner weakened to the point that they are reduced to small enclaves, leaving power vacuum in Underdark. Some drow follow new order, some return to Lloth.
d. Winner comes out of the war stronger due to new alliances/conquests and magic and starts to turn their attention to the surface.
e. Lloth turns all into driders and her avatar leads them in an effort to conquer the world.