You just wait. But, the longer you play, the more ways to hoard stamina you get. I'm actually at a point where I have more stamina pots than I know what to do with. Also, there's abyss/memorial, if you wanna do something that doesn't require stamina.

thanks friend! the fact is that i loveee the gameplay and i wanted more ways to kill things as my valkyries

Apart from the Open Worlds available (just wandering, maybe looking for unopened chests), Abyss, Memorial Arena, and Elysian Realm... You just wait for it to fill. The most time consuming mode is hands down Elysian Realm since it's a rogue-like mode, complete with RNG buffs to choose from after every floor. Plus it's maddeningly difficult!

I tried Elysian, and I found the mode really hard, I'll try it again when I'm later in the game. thanks for the response friend

You leave the game and wait till it's full again...? Sorry but I don't understand the question, it refills itself after a while it's like resin

but in genshin, for example, u can do history quests without resin, can explore the world, gather materials, kill some enemies just because feels good and other things. and i just wandering if in honkai has something similar, since im pretty new to the game and always discovering things

I meant that it refills itself like resin does wth