If for some reason a woman remarry her husband or repeat the nikah does this invalidate the marriage, it was extremely necessary for them to repeat the nikah

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

You did not explain to us the reason for renewing the marriage contract, but in general there are three cases to consider:

First, that it was an invalid marriage by consensus, like marrying a woman during her ‘Iddah [post-marriage waiting period] or the like. Such marriage is given no consideration and it is as if it never existed.

Second, that the marriage’s validity is controversial, like marrying without a Wali [legal guardian]. This case has consequences, like that divorce in it is effective, and the like. For more benefit, please refer to Fatwa 90025.

Third, that the marriage is valid and fulfills all conditions clarified in Fatwa 83629. Renewing the contract here has no effect on the first contract.

Allaah Knows best.