In answer to your question, you could pour the last of the old bottle into a new bottle.
This is something to think about. This was in an article on the Internet; I snipped a portion ...
"Take a look at your favorite cleaners - what's in them that makes them really work well? I had to hit myself over the head for this one! My favorite cleaner is Clorox Cleanup with Bleach. Why am I not just trying the bleach by itself? Why do I still feel like I need the miracle cleaner? Sometimes it is hard to change when we are conditioned by commercials. They tell us we need these miracle cleaners that are strong enough to kill microbes on Mars but still have a "lemony fresh scent." I think the key to any change is to make the transition gradually. In this case, you do that by replacing your store bought cleaners as they run out and ignoring those commercials!"
Look on your Clorox Cleanup bottle and see what some of the ingredients are ... what's listed first are the main ingredients.
I have mixed up small batches of Chlorox diluted with some water, add a tad of detergent and fill your own bottles and see how it works! It is a whole lot cheaper.