Allah is The Most Merciful Who showers His Mercy on us all the times. He wants us to avoid sinful acts and never insist on wrong, so that He forgives our sins when we sincerely repent and seek forgiveness. Sinners who insist on doing wrong and never care to repent, will face the results of their own deeds. Allah's Mercy does not allow punishment for sins we have repented, nor repeating a punishment which has already been given.
The Mercy and Forgiveness of Allah, is above our imagination. His Mercy and Forgiveness will be on The Day of Judgement for almost every one except the enemies of Allah, the Prophet and Ahlul Bayt. Enemies of Allah will be facing the results of their crimes in their graves and in the Day of Judgement as well, but sinners who are not enemies of Allah will not suffer twice. Grave for some believers is a place of purification so they suffer in the grave to go pure in The Day of Judgement.
We need to have more hope in Allah's Mercy and keep ourselves away from sins and seek forgiveness.