I bought the game from Epic Games but I'd like it in my Steam library. Is there a way to activate the game in steam without having to repurchase?

No.

Originally posted by Kered:

I bought the game from Epic Games but I'd like it in my Steam library. Is there a way to activate the game in steam without having to repurchase?

Nope, they are competing companies so if you want it on Steam, you'll have to buy it here as well unfortunately.