Having been poisoned by River Song the Doctor enters the TARDIS and has a discussion with the voice interface, while attempting to find ways to survive, The Doctor asks if he should regenerate, to which the interface replies that regeneration had been disabled. I can buy that the Doctor faked his regeneration at lake silencio using the Teselecta (just), as there were people present he didn't want to know about The War Doctor, but why go through the pretense when he is alone in the TARDIS?
There is no way to know. First, let us look at exactly what the Doctor says:
INTERFACE: Your system has been contaminated by the poison of the Judas tree. You will be dead in thirty two minutes.
DOCTOR: Okay. So, basically better regenerate, that's what you're saying.
INTERFACE: Regeneration disabled. You will be dead in thirty two minutes.
DOCTOR: Unless I'm cured, yeah?
The Doctor doesn't ever ask if he "should" regenerate. Speaking for the TARDIS, he assumes that it is going to suggest regeneration as the optimum course of action in that situation. Technically, we gain no insight as to his awareness of his own life cycle in this instance, so it is impossible to say. For all that we know based on what little there is to work with, had the poison not disabled his regenerative system altogether, if the TARDIS had suggested that he should regenerate, then he could have very well have taken that opportunity to mention the fact that he was out of lives and that the TARDIS needed to think of an alternative. But because the opportunity to elaborate on his position is preempted by the poison having disabled his regenerative capabilities altogether, we never reach that point in the conversation. Once he is told that regeneration isn't possible anyway, he immediately moves on to the next option.