Getting NI number when returning to UK

I previously lived in the UK on a spouse visa (2009-2012) and had a NI number.

I am applying for another spouse visa to return to the UK.  Will I need to apply for another NI number or resume using my previous one?

Thanks for any advise or links you could share

You use the same one.

Try here if you've lost your previous NI number,

https://www.gov.uk/lost-national-insurance-number

fill in this form and mail it to the address in Newcastle on the form.

http://www.hmrc.gov.uk/forms/ca5403-static.pdf

This is what we did to find my wife's old NI number.