Q:

Silverlight: Make part of a storyboard repeat

Is it possible to create a storyboard where the second half repeates, but the first half doesn't?  Or alternatively, can I cause one storyboard to start after another finishes, all in xaml?

A:

I don't think you can work with animations just in XAML/Blend you need to begin them in code anyways.
StoryBoard1.Begin();

But the code to start another animation just as the first one finishes is quite simple:
First you subscribe to the Completed events in code:
this.Storyboard1.Completed += new EventHandler(Storyboard1_Completed);
this.Storyboard2.Completed += new EventHandler(Storyboard2_Completed);
this.Storyboard1.Begin();

Then in the respected eventhandlers if Storyboard1 finished you start storyboard2 and vice versa.
private void Storyboard2_Completed(object sender, EventArgs e){
        this.Storyboard1.Begin();
}

private void Storyboard1_Completed(object sender, EventArgs e)
{
    this.Storyboard2.Begin();
}

To add the eventhandlers you just have to type Storyboard.Completed += and then hit tab twice and it will generate the needed methods.

