In The Two Towers it reads:
Shelob was gone; and whether she lay long in her lair nursing her malice and misery, and in the slow years of darkness healed herself from within, rebuilding her clustered eyes, until with hunger like death she spun once more her dreadful snares in the glens of the Mountains of Shadow, this tale does not tell.
The Two Towers -- J.R.R. Tolkien -- chapter X, The Choices of Samwise Gamgee
The LOTR Wiki says it's unclear what happened to Shelob after Sam wounded her so severely, but I am inherently mistrustful of the accuracy of series Wikis. I don't have The Silmarillion so I thought I would ask here: Did Shelob die? Is there any canon information regarding Shelob's ultimate fate?