So you can just use a template in your request like

<tokenPassport xmlns="urn: messages_2017_2.platform.webservices.netsuite.com" xmlns:ns1="urn:core_2017_2.platform.webservices.netsuite.com">
    <ns1:account>{{account}}</ns1:account>
    <ns1:consumerKey>{{consumerKey}}</ns1:consumerKey>
    <ns1:token>{{tokenId}}</ns1:token>
    <ns1:nonce>{{nonce}}</ns1:nonce>
    <ns1:timestamp>{{timestamp}}</ns1:timestamp>
    <ns1:signature algorithm="HMAC-SHA1">{{signature}}1</ns1:signature>
</tokenPassport>

and every time you submit the placeholder variables are automatically calculated