how to renew idp-signing.crt in powershell o365 (federated)?

Question

How to renew signing.crt (idp) file in Federated O365 ?

$cert = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2("C:\Users\test-win\Documents\idp-signing.crt")
$certData = [system.convert]::tobase64string($cert.rawdata)
$certData
Set-MsolDomainAuthentication –DomainName $dom `
    -FederationBrandName $fedBradName -Authentication Federated `
    -PassiveLogOnUri $url -SigningCertificate $certData `
    -IssuerUri $uri -ActiveLogOnUri $ecpUrl -LogOffUri $logoutUrl `
    -PreferredAuthenticationProtocol SAMLP