I'm A Banana
Potassium-Rich
If you get lost in the mountains, is there anything stopping you from finding a trail? No. So yeah, you can try again. (You might be too late to stop the slavers you're chasing from reaching the crossroads, though.)
Well, personally, I'd say what stops you from trying again is the fact that you failed to find one in the first place. That failure means that any trails that may exist are beyond your skill at this point.
Effectively, it's the skill challenge determining the reality of the situation. Are the mountains too hard to cross? I don't know -- here's a skill challenge. If you fail, then they are too hard to cross, and you need to do something else. It's a level of abstraction. You get one chance to find the path, and if you fail, you don't just get to take an extended rest and try again. If I give the party a TPK, they don't get to just take an extended rest and try again. They have to do something else.
The penalties for failure should be permanent and irrevocable, IMO. Otherwise, you might as well not have the challenge in the first place -- players can just keep trying until they roll 20's and get through.
I like the way Burning Wheel deals with this: When the situation changes enough. You failed to cross the mountains because an avalanche blocked the pass? Wait for summer.
When does the situation change enough? That requires a judgement call from the DM. That's fine, it's a good thing - it allows the DM creative input into the game.
That makes sense, too, but it's effectively the same idea: you lost this challenge, and if you want to try again, you have to have a different sort of challenge. You don't just get to repeat your attempt.