I do update our Lounge room every 2 years.I keep the main items, but I like to have a new lamp shade, as they tend to look tired.
Rugs are changed, and any cushions....and of course curtains too.Just so the place looks fresh, and also may paint ever 4-5 years.
I hate that live-in-look, where it all feels like if you sit down....something may
just 'bite-you'! yuck.
We don't update very often. We like what we have, and are tastes haven't altered, so why spend money to make changes. I like seeing the same furniture, and decorations everyday. Stick with the old, leave the new to someone else.
I don't really have too many to be honest. I only recently bought a cushion, otherwise I don't have many decorative things like cushions and rugs... so there's no need to update them. When I do buy things I tend to try and find cheap ones that look good. Sometimes I've found some good stuff at Target.