Hi ~ I'm sorry about your dog...they leave such big holes in our hearts when they depart.
Though others in your area can better address your rescue concern, I'd recommend Petfinder as a starting point. That site lists rescues and, I believe, identifies those that are breed-specific. Though you can also find a pure bred Lab in a regular rescue or shelter.
You'll know when you're ready. If you're questioning it now, you probably aren't....but you're ready to start looking into it (see above).