Is my marriage null, given that I kissed my wife and did other things with her during the engagement period, and later learned from Surat An-Nur that fornicators do not marry except a fornicatress or an idolatress, knowing that I have been married for eight years? And is it permissible to renew a valid marriage contract without a legitimate Sharia reason, as some people do in Pakistan?

Renewing a valid marriage contract is not legislated merely due to doubt. What was mentioned about a man kissing a woman during the engagement period and masturbating with her hand before the contract is forbidden. However, after the contract, there is no harm in it. The marriage of फॉरnicators to each other is permissible after the 'iddah (waiting period) and the repentance of each of them, due to the Almighty's saying: (Impure women are for impure men, and impure men are for impure women, and pure women are for pure men, and pure men are for pure women). A marriage contract may not be concluded except after the 'iddah and ensuring the womb is clear of pregnancy. In this case, there is no need to repeat the contract, but repentance to Allah is obligatory for the forbidden enjoyment that occurred before the marriage contract.