:) it's fairly easy to break up the clumps, actually- it grows like hair, straight up until its own weight flops it over. you can either mulch the 'part' where the stems have turned woody (last year's growth and the shaded bits) or just find the crown under all that growth, lift it, and split it in to two or three clumps, then replant them a foot or so apart- each will fill in to be the size the master clump was next year.

I don't like to lift plants during the heat of the year- but this spring has been plenty mild for such things. doing it in july would be another story.