You could use the following code, it does a recursive call into the function in order to properly wait for the desired time.
function exportar(page,miliseconds,totalpages)
{
if (page <= totalpages)
{
nextpage = page + 1;
console.log('fnExcelReport('+ page +'); nextpage = '+ nextpage + '; miliseconds = '+ miliseconds + '; totalpages = '+ totalpages );
fnExcelReport(page);
setTimeout(function(){
exportar(nextpage,miliseconds,totalpages);
},miliseconds);
};
}