"Remembrance" is a loaded word in Brontë's elegy. It means way more than just remembering or forgetting.
Sure we might remember the time we locked our keys in our car or forgot to turn the water off while running a bath, but that's not remembrance. Remembrance is a tad more complicated than all that. It's not as simple as something slipping our minds; it's about remembering and memorializing the dead. Which is tougher than it sounds because sometimes we may want to forget our pain but would never want to forget the love we felt.
Before even getting to the poem, we've got all sorts of ideas running through our minds related to remembrance and what that means to us. We may even feel a bit overwhelmed at times. Sure these may be some heavy thoughts, but Brontë's got it covered.
See, "Remembrance" is deliberately constructed to be a tour de force in the world of memory, time, and the human mind. And as we know, such ambitious projects aren't supposed to be easy, especially when you're working with a title as broad and loaded as "Remembrance." Oh and lots of other poets, including the Romantics like Shelley and Byron, had previously published poems with the same title, which Brontë would have definitely read. So Brontë was probably looking to take a stab at it, too.