What if I keep asking God to forgive the same sin?

Struggling with the same sin repeatedly, while genuinely wanting to change, is different from deciding in advance that forgiveness makes the sin fine to keep doing. Both can look similar from the outside. They aren't the same thing.

Paul himself describes this exact struggle—wanting to do good, doing the opposite anyway, hating that gap in himself. He doesn't treat that struggle as proof he wasn't really a Christian. He treats it as part of an ongoing fight, one he hadn't finished yet.

What Paul does reject is using grace as a plan: sinning on purpose because forgiveness is available anyway. That's a different posture entirely—not struggling against something, but leaning on grace to excuse it.

If you're tired of asking God to forgive the same thing, that tiredness is usually a sign you're still fighting, not evidence you've failed. Keep asking. Keep resisting. That combination is what the ongoing fight actually looks like.