Racking Apple Ale to Secondary, plus a question

So, a brewed 4 gal. of wort, then added a gallon of apple cider (couldn't find unpasteurized, but used Trader Joe's preservative-free) once the fermentation got going. A week later I'm racking to secondary, but there's more than 5 gallons somehow.

So what can I do with 3/4's gal of wort? For now I just re-sanitized and put the lid back on the primary, but I'm hoping to come up with something more entertaining.