Sometimes it's too much hassle to "redo" existing anchors (e.g. you may have created a link where you don't have easy access to change it; even if you do have access, I think it would depend on how often these indexed links were crawled), so it may be just be easier to add new links to increase the anchor text variation.Would you (if you could) redo the anchors on existing links or create new diversified anchors (click here, url etc.) to lessen the percentage of the optimized anchors?
My fear is that the penalty will not be lifted even if the ratio is changed by adding new diversified anchors.