How Do You Reply to Deadend Text?

Changing the subtopic like that makes me feel nosey, and the conversation starts to feel one sided. (His answers aren't super short, but no prodding of any kind.)

I'll try sub topic changing next time I hit this wall, and see how it goes. If it starts to feel one sided, I'll try for an exit. "You sound busy, ttyl" or something.

Thanks guys.

Well, if you do want to keep up the conversation, you have to be involved. The fine line between being involved and being nosey is yours to define. For a better chance at receiving response, you should try to scratch where it itches, not just shooting in the dark.
Like if he's stated that he's OCD about training, you can ask what his objective is regarding the final levels of his pokemons.