"Can I Try Again?"
When you roll dice, we assume you're already doing your best, so the answer is: "It depends."
Something needs to change before another attempt makes sense. Find a better approach, get help from an ally, or discover new information. Create a Boost - a preparatory action that improves your position for the next roll. If you have a better EL, you can try again unless the GM thinks you're just metagaming the system (this isn't a video game.)
Without change, you'd just get the same result. The exception is when the GM tells you your effect accumulates.