My 2-year-old is now capable of making certain phonetic sounds that he wasn't able to when he first started speaking.

For many words, he's adjusted his pronunciation slightly as he's used them more often, and we've not had to do any training. For other words, he continues to use the old, incorrect pronunciations despite his apparent ability to do otherwise. We tend to rely on repeating back complete sentences with proper pronunciations, or just having conversations where we slip in the target words, rather than doing any explicit *correcting*.

Specific examples:  

He calls Captain America "Cappa Nappa". But, if I ask him say the words more slowly, I can get a "Cappin Uh-merta", which is closer and we're very happy with it. 

When he first started referring to the TV he called it the "Deet" (a "word" he also used for other things). He can now say something like "Tee wee" or "Tee fee", but now he'll just say "Watch movie" or "Watch show", opting not to say TV at all.

We know he can pronounce the words better, but seems to be attached to the older pronunciations. This may just be because the older pronunciation is physically easier for him to say, or because we understand him well enough with his improper pronunciation, it's simply habit, or most likely a combination of all of those.

**How can I effectively coach, train, and/or encourage my child to pronounce words in a new way, now that he's physically and/or cognitively able to make new sounds?**

Or

**How can I effectively teach my child to stop using their "nonsense words" and instead use the real words they're now capable of saying, when they have a strong personal preference to avoid the real words?**

In our case, I feel that our son has demonstrated his ability to do better, but *chooses* not to because it *is* more challenging for him. I want to encourage him to try and tackle more challenging tasks.

We're very happy with his language development, and are more amused by or endeared to his mispronunciations than anything. But, I feel there are certain words we could more actively work on. Language is one of his primary learning activities, and I'd like to set the stage so that he's accustomed to having small challenges.