Hi, Lapras still worth to cost dust?

I'd guess probably not. I haven't seen a lapras in a gym in months. Although, I've used my ~1500s against some critters in a gym.

It might be worthwhile if you do not already have something for fighting enemy Dragonites.

Or you can leave it where it is and use it for prestige.

I have several Lapras. as much as he is not what he once was still eats dragonites and is a capable attacker or defender as long at the cp is high enough to get you past the ground floor. I would power it up.

Idc if Lapras is nerfed, I'll still use it in gyms. If this isn't your disposition then I would keep it as is for prestiging

I'd go for it. I absolutely love my 2 Lapras for taking down Dragonite.

As was said, If you don't have any good ice attackers, you should power it up. If you do, then don't. FB/Bliz is the best attacking moveset, and a 1500 Lapras can take out a 2500 Dragonite. Also, if there are no Dragonites in gyms in your area, the need is minimal.
Lapras/Ice is also good against grass, ground, and flying (as well as dragon), so things like Gligar and Celebi (eventually) could be weak to it.

Powering it up is up to you. It does in fact have a ideal moveset for attacking especially into dnites but you could also just use a lower cp ice type or even a fairy type and not have a problem so it's a matter of if you wanna power it up or not. I wouldn't use it as a gym defender though unless you plan to max him out but even then it's not worth it since that moveset is better for attacking not defending

Thats a great move set for attacking Dragonites. If you don't have a Lapras already then definitely power it up. I still use my 89% FB/B lapras that I maxed as one of my primary attackers and he will eat up a Dragonite no problem. I got a second one with the same moves but it's only 82% so I have elected not to power it for now because I don't have the candies and I have higher priorities for my buddy.

If you don't have one already juice that sucker up. I caught one months ago even smaller with IV62 IS/B and max it every time I level up. Now CP2202 it smashes the first 3 or 4 out of a gym, or the top beastie. Have only ever caught two so had to walk 360km so far.

If you have a decent one already probably better to use as is and put those 5km candies into Larvitar.

I would only power up a Lapras if you already have the candies for it. I have walked a Lapras more than 240km and I regret it now that Piloswine, Cloyster and Jynx all do the same job. It's not that much worse than it used to be, but I'd rather walk something more useful like Chansey or Snorlax.