In asking this Peter no doubt thought he was being generous. Among the Rabbis, some explicitly taught that a man could be forgiven three times, but no more. But the grace of Christ extends far more. Which is to say, however many times the sinner sins against us, we must forgive him. Indeed, if we did not, no family or organization could stay together.
Daily forgiveness means daily confession of our sins.
It means daily repentance. The Christian life is a life of repeated repentance and renewal. We will always be sinners in this life and will always need to be renewed in our faith and repentance. The essence of perseverance is daily repentance for our sins and trust in the grace of God to save us. Our Lord's instruction connects our perseverance with our helping other Christians to persevere, for that is part of what it means to forgive others.