JSFiddle - React, Tailwind, and code Playground
JavaScript
chaine='{"CBR":{"Amount":4032.8183578,"conso_ccy_name":"EUR"},"LEPR":[{"RequestDate":"/Date(1365428270607)/","ThirdParty":"TP1","Amount":22,"Currency":"EUR","Status":"Pending"}]}';
alert(chaine.replace(/(Date\(\d+)(\))/,"$1-0000$2") )