If your Lebkuchen has become too hard, it is because it has lost moisture. Ergo, it simply needs to draw some moisture again to regain its juiciness.
For this purpose, we have listed 2 safe ways, approved by Pfeffer & Frost team:
Put your Elisen together with a few slices of fresh bread or half an apple in a sealable tin. After a few days, you'll have soft, moist Lebkuchen. It is important that you change the apple or bread slices every 2 days so that nothing molds.
And if you need to make them really quickly, just dip them in your coffee, tea or cocoa and they'll be soft and juicy again in no time, and you'll have the perfect snack for your coffee or tea time.