There is actually pretty good support, but you have to use AdSense through Google DFP - https://www.google.com/dfp/. Things like creating ad slots dynamically / loading them later / refreshing them dynamically work fine when you use GPT tags in DFP.
Afaik AdSense still explicitly prohibits refreshing through JS, but this doesn't seem to apply when going through GPT. I'm not entirely sure what the situation here is.
Case in point: I have an AJAX site where users spend about 18 minutes per visit and refresh ads every two minutes. So far no complaints from Google.
Interesting - is your site earning more than $1K a month? Just trying to gauge if you're big enough to get in their (human) crosshairs for more specific checks, or not.
Yes, their rules are a mess. However, as the OP mentions there was indeed an "AdSense for Ajax" beta several years ago, and refreshing ad slots was listed as its primary use case.
In my case, my site is structured as tabs. I refresh the ads when the user switches the active tab. A tab occupies about 95% of the page anyway.
