This is an old problem and unfortunately there is no way to do this with native way. The LESS compiler just watches modified files. So, if you are using a file with imports, this file needs modified and recompiled.
In development enviroment (with javascript) you can solve this issue putting this to clear cache:
<link rel="stylesheet/less" type="text/css" href="/css/style.less"/>
<script src="/js/less-1.1.5.min.js" type="text/javascript"></script>
<script>
less = {env:'development'};
function destroyLessCache(pathToCss) { // e.g. '/css/' or '/stylesheets/'
if (!window.localStorage || !less || less.env !== 'development') {
return;
}
var host = window.location.host;
var protocol = window.location.protocol;
var keyPrefix = protocol + '//' + host + pathToCss;
for (var key in window.localStorage) {
if (key.indexOf(keyPrefix) === 0) {
delete window.localStorage[key];
}
}
}
window.onload=destroyLessCache('/css/');
</script>
Reference: https://github.com/cloudhead/less.js/issues/47