Perfect - that works, thanks. I kind of expected it to do automagically, and I couldn't find the setting. The file's called "ClientDependency.config" in my system, and incrementing that number does the job - thanks!

For those who are, like me, on Visual Studio without a built server: I am using a simple gulp script which will update ClientDependency version on each build. This should work in Umbraco version 7 & 8.

Here is my gulp.js:

/// <binding BeforeBuild='BumpClientDependency' />

var gulp = require('gulp');
var debug = require('gulp-debug');
var xmlEdit = require('gulp-edit-xml');

gulp.task("BumpClientDependency", function (done) {
    return gulp.src('Config/ClientDependency.config')
        .pipe(debug({ title: 'updating ' }))
        .pipe(
            xmlEdit(
                // transform function:
                function(xml) 
                {
                    var oldVersion = parseInt(xml.clientDependency.$.version, 10);
                    var newVersion = oldVersion + 1;

                    // prevent Int32 overflow in C#
                    var int32Max = 2147483647;
                    if (newVersion >= int32Max) newVersion = 1;

                    console.log("Old version: " + xml.clientDependency.$.version);
                    console.log("New version: " + newVersion);
                    xml.clientDependency.$.version = newVersion;
                    return xml;
                },
                // options:
                {
                    parserOptions: {},
                    builderOptions: {
                        headless: true,
                        renderOpts: {
                            pretty: true
                        }
                    }
                }
            )
        )
        .pipe(gulp.dest('Config/'));
});

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