const regex = new RegExp('\\b\\d{7}\\b(?=(?:(?!\\b\\d{7}\\b).)*incomplete n/a).*?$', 'gm')
const str = `1281674 the crescent annandale 02/10/2019 16/10/2019 - 16/11/2019 pending 1281640 city west link rd lilyfield 02/10/2019 16/10/2019 - 16/11/2019 pending 1276160 victoria rd rozelle 25/09/2019 14/10/2019 - 15/10/2019 pending 1331626 31/12/2019 - 31/01/2020 incomplete n/a 1281674 the crescent annandale 02/10/2019 16/10/2019 - 16/11/2019`;
const subst = ``;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions