My amaryllis bulb is about 26 years old and blooms twice every year without fail.
I have it in an east facing window, and I water it as and when I remember!
I feed it with Gro-more twice a year as the main stalk starts to show (only adding to one watering each blossoming time).
I honestly do not pamper this bulb, never take it out of the window (even in winter but central heating usually keeps house at about 20 degrees), forget to water regularly (sometimes the leaves start to droop a little) and yet it still gives me 2 beautiful displays every year.
The bulb has almost filled the pot for the last 6 years, so I took it from the pot 6 weeks ago, cut back the roots
(there was very little soil left anymore) and put some new soil in.
I thought I had killed it
but it is proudly showing 4 deep red blooms on the stalk.
I do strip off the dead 'skins' on the bulb when it gets very flaky - a gentle pull brings most of it off.
Hope this helps.
gardening.stackexchange.com/users/11158/Jay Bee
I would re-pot it and fertilize it and keep it moist for a while, and if nothing happened in a couple of months, I would get rid of it.
gardening.stackexchange.com/users/419/J. Musser
my amaryllis bulb is now 21 years old
I leave it in a pot year round in the house some years it blooms twice
gardening.stackexchange.com/users/3250/Lori
My Grandpa has one in his living room that belonged to his mother.
She has been gone for 38 years, so we figure at the minimum
it is 40 years old.
He said it had 9 different blossoms this year but only blooms once per year.
gardening.stackexchange.com/users/11571/BenD
My mother started her Amaryllis in 1942.
My sister and I divided the bulbs maybe 15 years ago.
They didn't bloom for a few years.
Now mine blooms every year and my sister's has only bloomed a few times.
No explanation...
I remember it blooming as a child
and I'm 63.
So given its history it's 75 years old this year.
gardening.stackexchange.com/users/16746/Roger Owens
I have an Amaryllis plant.
It is planted in the ground in the back yard and has been there for over 50 years.
No special care, just watering.
gardening.stackexchange.com/users/14193/Brenda H
I'm going to guess it's a Hippeastrum as you're keeping it in a pot - Amaryllis is often planted outside, whereas Hippeastrum are not.
They can live for decades (my mum has one that is at least 50 years old).
They will go dormant for part of the year.
The main thing is not to overwater them or bury them too deep - my mum's has been half out of the soil.
If they sit in cold, damp soil they will rot.
Do not water them when they are dormant.
Six months sounds like a long time to be dormant.
Try shifting it to a warmer, brighter spot.
If nothing happens, try lifting the bulbs and have a look - are they firm and plump (like a fresh onion) - if so, plant them again and be patient.
If they're rotten or hollow, then I'm afraid you're out of luck.
gardening.stackexchange.com/users/16580/George of all trades
I've had an  amaryllis  bulb in a pot for about 5 years now and the bulb hasn't been doing much for, I reckon, over 6 months. When should I consider getting rid of it? Could it have run its course?
How long do amaryllis bulbs live?
gardening.stackexchange.com
<plant-health><bulbs><amaryllis>
gardening.stackexchange.com/questions/2979
gardening.stackexchange.com/users/800/Alex G
They can live for decades. Amaryllis can live for decades up to at least 75 years old and be passed on through generations.
Amaryllis bulbs can be over 20 years old and bloom twice every year without fail. S1: They can live for decades up to at least 75 years old and be passed on through generations.