You can look for very high and many many strands as possible for probiotics. There is one by Renew Life that has like 50 Billion. It's refrigerated. I've learned those are the best. They are pricey, but probably worth it.
Another suggestion, start drinking Kefir. It seems to be absolutely fabulous for colonizing/repopulating. Very powerful and good for you. I have started to make my own, havent' perfected the technique yet, and drinking the brand Lifeway until I get it down. Making your own Kefir is the most beneficial and powerful thing you can do. You can buy the grains online, or if your lucky, find them from a friend or locally.