Just a couple ideas to give replayability a boost.

I don't want people to think that I'm saying Valheim doesn't already have excellent replayability because it is genuinley one of the few games out there that I can just play and play and play. Valheim is absolutley one of the best games of its genre to come out in a very long time. There's always something to do to keep the experience interesting and fun and I have a few ideas here to give that just a little more oomph:

Separate trophies for 1 and 2 star NPCs.

Given just how rare it is to see some 1 or 2 star variants on certain enemies(in 600 hours of gameplay I have literally only seen one 2-star troll) I think the drop rates of the separate trophies should stay the same as their regular counterparts. This would encourage more exploration of previous biomes, give us more stuff to decorate our homes with, and give players huge bragging rights in multiplayer.

Vanity-switching armor pieces without losing out on bonuses or armor rating.

One thing that bothers me about most RPG games is when players all start looking the same. Everyone's wearing the same armor within their armor class and I personally think it's a bit boring. World of Warcraft(and probably a couple others) has a brilliant mechanic for preventing this called "Transmogrification". The ability to let players change the appearence of any armor piece to another(within its armor class). This gives players thousands of choices to make themselves look however they like and the art pieces people come up with are amazing. When I played World of Warcraft I spent HOURS planning for new transmog sets, researching and hunting for the pieces, and then doing it all over again. It was SO much fun. Just personally I found I never played so well than when I was satisfied with how cool my character looked.

I suggest a similar system to World of Warcraft and I think I've figured out a way that could make it possible in Valheim without breaking anything.

The Artisan Table currently doesn't do much except make ballista ammo but I doubt IronGate doesn't have plans for it in future. So I propose that the Artisan Table be given special recipes which allow the changing of the appearence of armor pieces. Here's an example as to how:

10 Refined Eitr, 2 Wolf Pelts, and 2 Drake Trophies makes you the "Artisan Drake Helmet".This item would have zero stats and wouldn't be able to be placed on any item stands. You'd then right-click this, it would take a good 10 seconds to complete(ample time to change your mind or cancel the decision if you clicked by accident) and it would permenantly change the appearence of your currently EQUIPPED head piece to that of the Drake Helm and place the icon of the Drake Helm in the bottom right of the stats window. To undo this change the player would place the head piece into the Obliterator, pull the switch, and what would be left would be the armor piece with the appearence change removed and the Artisan Drake Helm item would be destroyed. There are currently 44 different armor pieces in the game(without counting diffrent colored capes, Dverger Circlet, Yule Hat, and the hat and cape for the beta testers) making up 11 different armor sets(with more to come) so someone else can do the math on how many potential armor "sets" we could have if we could change their appearence and still keep their set bonuses and armor ratings.

Like I said, Valheim doesn't necessarily need better replayability but if it has more stuff that's fun for the players then what's the harm in that?