If you liked the game for what it was last time, you will still like it now. If you didn't, or it wasn't enough, then you might still not like it now.

Wait until mistlands release

Start a home world save, where you kill no bosses and bring resources from other worlds into. It's very chill knowing no serious invasions might happen.

I think you should play just for old times sake. Who knows you may discover something new.

If you feel an itch to play, play. Valheim is a good game and you will find new stuff throughout. People who say nothing has changed are children who don't know the difference between hyperbole and reality.

But if your need for novelty is strong, you might wait until Mistlands drops.

Lots of more building options, but progression wise almost no change yet.
If you like building structures, then the game is absolutely worth playing again for the new stuff added. Building more complex and good looking buildings.
If you like progressing through the game and killing bosses, its not worth picking up again at the moment. The last major update has almost been a year ago, so i cant imagine it taking much longer for Mistlands to drop and add more progression for those that want that.

Mods are quite fun, and very extensive. Just make sure the mod is up to date with hearth and home and you won't have much trouble installing and playing.
I use manual plugins, but there is a mod manager for valheim as well with thunderstore and it's mods. You can use the mods from both thunderstore and nexus pretty easily with manual plugins, so don't worry too much about it having 2 sites to download mods from.

wait another year. hopefully more things will be added but so far not enough to start a new playthrough

wait. Pretty much zero change since release

Mountain caves probably.

not enough new stuff. wait

New building materials, and the mountain caves. The food system had a major revamp, so you need to adjust to that. No problem if you start from scratch anyway.

Ah, yes, the swamps feature a new mob. Not going to say, what. :D

I started a a new game last month, killed Bonemass, and have been working in the mountains. So far, hasn't been worth the trouble. Basically the same experience as sixteen months ago.

If you're hankering for that experience again, go for it. It still holds up. But if you're hoping for something new and substantial, we're still waiting for it.

The food system is likely the biggest change, and is a game changer in early game (IMO).

Also, don't forget there is a new mob in plains as wall, along with the associated building parts that it brings.