Will Allah forgive us for a sin that we commit knowing that it is haram but we plan to ask for forgiveness later? For example, I know what I am about to do is haram but I have a plan to ask for Allah's forgiveness later after committing the sin. Later I ask for forgiveness for committing that sin.
This is two sins. One is the original sin and another is minimizing God position. A real believer does not minimize the value of God by such plan.
Also this is a deception from Satan to catch believers. By this deception, humans commit more and more sins by planning to ask forgiveness later. This period keeps extending and becomes harder and harder after each sin to ask forgiveness, until death takes place immediately and Satan becomes successful.
This is a deception from Satan and should be avoided.
Minimizing God itself is a major sin.
Ahl al Bayt said:
Do not look at small size of sin, but look at greatness of who you are disobeying him.
None of us should be disappointed from mercy and forgiveness of God but it depends on if our asking forgiveness even happen or not and if happened in later if it is a real one or not.
O my sons, go and find out about Joseph and his brother and despair not of relief from Allah. Indeed, no one despairs of relief from Allah except the disbelieving people." http://tanzil.net/#12:87
إِنَّ اللَّهَ لَا يَغْفِرُ أَن يُشْرَكَ بِهِ وَيَغْفِرُ مَا دُونَ ذَٰلِكَ لِمَن يَشَاءُ ۚ وَمَن يُشْرِكْ بِاللَّهِ فَقَدِ افْتَرَىٰ إِثْمًا عَظِيمًا
Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills. And he who associates others with Allah has certainly fabricated a tremendous sin. 4:48
This Aya(verse) is clearly stating that ALLAH will forgive us for whatever you did unless association with him But this doesn't mean to commit a sin and say to yourself that I'll ask Him for forgiveness.
This act is insistence on guilt and this will cause to association in some means. Also be aware who said that you can repent from your sins after you commit it?!!!
History and Qur'an stories told us about many examples who commit a sin and thought that they will repent from. You know the story of Youssef's brothers, they throw him in the well and they think that they can repent but they can't do that...
Be aware that the insistence on guilt make the small sins a large sins, and you can't easily revert that fact and by time the heart get more black and once will reach a time that he can't repent, for that this insistence will lead to the association.