Some of these little ones also respond well to supplimenting utterances with simple words in sign as they speak. It seems to help them sequence where words go and takes the "talk right" pressure off, because they can vocalize with the sign and be understood. As the speech develops, the sign naturally drops. We have had kids in a birth to three program who got verbal words much more quickly when they could sign "more" then "more milk", always with the expectation and model that voice goes with signs. The adults have to use it consistently too. If they have complex things to relate, use a photograph of the book, play center, etc. that they want. Again you expect and praise any vocalization that goes with the picture pointing. If you get only an "uh", model something simple but appropriate to say as you "repeat his pointed utterance". The words, being more efficient, usually come quickly with bright kids. And these activities even seem to help process the oral motor sequences somehow. Brains of little ones are so plastic and wonderful.
The treatment program for children with speech apraxia must be individualized and flexible. Here are some general strategies I have used effectively over the past 15 years for children with developmental speech apraxia and normal hearing. I hope these ideas will be of some help to you.