Force a computed property function to run

I realized my first answer missed your point, and won't solve your issue.

The problem is that a computed will only reevaluate if there is some observable that forces it to re-evaluate. There is no native way to force a computed to re-evaluate.

However, you can get around this with some hackery by creating a dummy observable value and then telling its subscribers that it has changed.

(function() {

    var vm = function() {
        var $this = this;

        $this.dummy = ko.observable();

        $this.curDate = ko.computed(function() {
            $this.dummy();
            return new Date();
        });

        $this.recalcCurDate = function() {
            $this.dummy.notifySubscribers();
        };        
    };

    ko.applyBindings(new vm());

}());​

Here is a Fiddle showing this approach

There is a method to force recalculation of all observables depending on yours:

getCurrentValues.valueHasMutated()