So far the refresh is not avaible for a production PowerBI Javascript release, you can check Missing a “Refresh” method to efficiently refresh a report/tile. You shall wait for the release.
You can try to re-embed the report to do the refresh, this would refresh the data from directquery based on my test.
<html><script src="https://microsoft.github.io/PowerBI-JavaScript/demo/bower_components/jquery/dist/jquery.js"></script> <script src="https://microsoft.github.io/PowerBI-JavaScript/demo/bower_components/powerbi-client/dist/powerbi.js""></script><script type="text/javascript">
var embedConfiguration = {
type: 'report',
accessToken: 'yourTokenHere',
id: '4c42a9f6-3ef4-xxxxxxxxxd5d6ebdac79d',
embedUrl: 'https://app.powerbi.com/reportEmbed?reportId=4c42a9fxxxxxxxxx-91f5-d5d6ebdac79d'
};
var report;
window.onload = function () {
var $reportContainer = $('#reportContainer');
report= powerbi.embed($reportContainer.get(0), embedConfiguration);
}
function reloadreport(){
var $reportContainer = $('#reportContainer');
powerbi.embedNew($reportContainer.get(0), embedConfiguration);
};</script>
<button onclick="reloadreport()">Click me to refresh</button><div id="reportContainer"></div></html>