Manually render dynamically generated Google 'plus one' button
You're on the right track. gapi.plusone.go() is one way to explicitly render the +1 button. Here's a code snippet from the official docs that illustrates another method using gapi.plusone.render().
<html> <head> <title>+1 Demo: Explicit render</title> <link rel="canonical" href="http://www.example.com" /> <script type="text/javascript" src="https://apis.google.com/js/plusone.js"> {"parsetags": "explicit"} </script> <script type="text/javascript"> function renderPlusone() { gapi.plusone.render("plusone-div"); } </script> </head> <body> <a href="#" onClick="renderPlusone();">Render the +1 button</a> <div id="plusone-div"></div> </body></html>The JavaScript API is further documented elsewhere on the previously linked page.