I would first get a better loop material. Allen makes a very good string loop material. They come in a three pack and are not burned so you can custom your loop to the size you want.It's afirm and thick loop material so it will hold it's shape and won't wear out.

You can also try to attach your release before the deer get that close. I usually attach mine as soon as I hear something moving. Sometimes I will even sit there with the released attached. I never hang my bow, it's always in my hand resting on my lap. I never want to miss the opportunity to get a shot because I have to reach for my bow.

Good luck, I hope you get another crack at him.