After collecting the ingredients and making the Juice he will drink it and give you a bottle, if you choose the first option, "What do I do when I see the Rift?", and continue with the conversation you'll be able to converse with him again. If you chose the other two options, you won't be able to converse with him again.
If you did the former and talked to him the dialog will start with him drinking the Juice and giving you another bottle, as long as you keep choosing the first option you'll be able to talk to him again and get another bottle.
I'm at level 11 with my Effective Biology at 36, with five minutes of my time I was able to gain a lifetime supply of The Juice.
