I'm just wondering whether if you still are or not, I think that would so unfair if he/she is still be killed.
No the sentence of death would not be carried out if this is the case. Under the Shariah, if a person openly goes out of Islam then the punishment for this crime is death, but before the carrying out of the sentence, three days is taken to discuss/talk/convince him to repent before the punishment is applied, if he/she refuses the punishment would be carried out, if he/she repents then the punishment would not be carried out and may Allah accept their repentance.
No. Under the Sharia law (al-Hadd or hudud) the person who became an apostate (riddah/murtad) must be warned for a period of times (there are alot of views on this period of time, some says 3 days, 3 months etc) to revert back to Islam.
After the period of time ends, if he still refuses to revert back to Islam, then he shall be sentenced to death.
Say, "O disbelievers, I do not worship what you worship. Nor are you worshippers of what I worship. Nor will I be a worshipper of what you worship. Nor will you be worshippers of what I worship. For you is your religion, and for me is my religion." - Quran 109:1-6
Also see Quran 2:256 with a similar message that there is no compulsion in religion.
Point being, there is no death sentence either way because Quran itself states that religion is not compulsory. Sharia is derived from various sources, but as a Muslim you should stick to what Quran says.
"In light of the texts (Qur'an and prophetic traditions) and the way the Prophet behaved with the people who left Islam (like Hishâm and 'Ayyash) or who converted to Christianity (such as Ubaydallah ibn Jahsh), it should be stated that one who changes her/his religion should not be killed. In Islam, there can be no compulsion or coercion in matters of faith not only because it is explicitly forbidden in the Qur'an but also because free conscience and choice and willing submission are foundational to the first pillar (declaration of faith) and essential to the very definition of "Islam". Therefore, someone leaving Islam or converting to another religion must be free to do so and her/his choice must be respected." (Tariq Ramadan on Apostasy)
Both Ibrahim al-Nakha'i and Sufyan al-Thawri were of the view the apostate should be re-invited to Islam, but should never be condemned to death.
Source: Chapter: Freedom of Religion in Mohammad Hashim Kamali’s Freedom of Expression in Islam Islamic Text Society, 1997
Also I think you might find this link useful it's sites various various respected scholars showing that apostasy is not punishable under Sharia
Sentence to death of a person who leaves Islam, is not valid after the time of Prophet Muhammad (PBUH). Since, the death sentence is not valid now, if a person comes back to Islam, then it is nothing more than a blessing of Allah on him.
A prophet (rasool) is God's "hujjat" (ultimate proof) on this earth. He clarifies the God's message, to such a degree that there is no valid reason to deny him and his message. A time comes in prophet's struggle when his nation openly denies him. After that time, the prophet's nation is under God's wrath. Thus, ONLY the believers are saved and every single person who is non-believer is killed. This is a proof of prophet's truthfulness and it is a "sunnah" of God that has manifested itself, time and again, ONLY during the presence of prophets.
It is usually done by a catastrophic natural disaster. Qur'an alludes to many such events of the prophets. The other way of God's wrath comes from the believers themselves. This only happens when the companions of the prophet are sufficient in number and also have a political governance.
In Prophet Muhammad (PBUH) case, the nation of the prophet in Makkah was under God's wrath when he emigrated to Madina. He got enough following and was able to make a small "state" in Madina. Thus God chose the second way to punish the non-believers.
Since the nation of Prophet Muhammad (PBUH) was already given a sentence to be punished to death, this became a precursor to the ruling that if a non-muslim ( of Prophet Muhammad's PBUH nation) tries to save himself by declaring Islam and then later denies, he is to be killed. Later on it was generalized for all time, while this rule is only specific to God's sunnah during the life of the prophet.
Thus death sentence of an apostate is not valid.