Question about lyrics

[Chibi_Venus]

Sometimes I notice that Ayu uses an extra word(??) in her lyrics when she repeats a chorus, although the translation is the same. For example, Memorial address:

sayonara ne mou nidoto aenai basho e itta none

However, the repeat of this chorus reads,

sayonara ne mou nidoto wa aenai basho e itta none

Something tells me that the "wa" is sort of just thrown in there, almost like an extra "la." (Unless I'm not hearing a "wa" at all, but rather an "ah." Just like the line kikasete hoshikatta uso de kamawanai kara where it sounds like a "no" was thrown in after "hoshikatta," but I guess that could be like a "whoa?") But then I was reading the lyrics to everywhere nowhere:

dokoemo ikezuni

But the final chorus is,

dokoemo ikezuniita

Here, it almost seems as if the "ita" isn't just thrown in (because of the way the music flows), although I guess it could've been thrown in.

I only wonder if these are thrown in because I once read that "nee" is sometimes thrown in as like a "hey" or "yeah," and that it doesn't necessarily mean a particular word. Just throwing in my background knowledge, there.

I hope I was clear on my question. ^^''