I have remained refrained from intercourse with my wife for 7 months, as she had given birth to my child and after the pregnancy she was not ready for it. Can I go for intercourse with her or do I have to renew my Nikah?
No question of renewing your Nikah. Your Nikah remains valid no matter how long you don't have intercourse with your wife, even if you are separated for years.
'Nothing in Islam suggests that you should refrain from sexual intercourse with your wife during her pregnancy. Even after child birth, you are allowed sexual intercourse immediately after the post natal bleeding which is ten days or less. Unless your wife is not well.
Wassalam.