When is "na" used at the end of a sentence, is it like "ne" or "yo" and has no meaning really? For example:
Mata Nihon ni ikitai na.
な at the end of a sentence usually gives the sentence one of the following five meanings.
1. Seeking confirmation
This usage is probably the most common. The addition of な to the end of a sentence gives the sentence the tone that the speaker is seeking confirmation. The speaker does not wish to assert that he is 100% confident about what he is saying. It does not necessarily mean that he isn't confident, he just doesn't wish to convey that he is. He wants to give his audience room to disagree if they want.
An simple example to illustrate some possible translations:
This book is really interesting don't you think?
This book is really interesting, right?
This book is really interesting, isn't it?
な as used this way is essentially equivalent to the sentence final particle ね except it is harsher and more masculine sounding.
This usage is related to the first usage (actual Japanese speakers might not consider them different) except it doesn't translate well into English. This usage essentially serves as a way for the speaker to reduce the assertiveness of a statement without actively seeking confirmation. In usage 1, the speaker is expecting the listener to say something and agree with him. In this usage, the speaker isn't necessarily expecting anything, he just wishes to introduce a topic without making an abrupt statement.
Consider the difference in tone between the following:
I would like to go to Japan again. (picture a person stating that as a fact with a completely expressionless face).
I'd reaaaaallllyyyy like to go to Japan again. (said with "really" drawn out and with changing pitch).
They essentially mean the same thing but the first is merely a statement of fact while the second is almost about introducing a topic.
This is the use in your question and the second example above is a reasonable translation (the "reaaaaalllyyy" should not be in the translation and was only included to illustrate the tone).
3. Negative imperative (Rough)
The addition of な to the dictionary form of a verb produces the negative imperative (command). This is very harsh and not used often in actual conversation I think.
食べる｛たべる｝な! - Don't eat it!
行く｛いく｝な! - Don't go!
A more acceptable negative imperative would be:
食べないでください。 - Please don't eat it.
行かないでください。 - Please don't go.
4. Positive imperative (informal and abbreviated)
The addition of な to the masu-stem (i-stem, ます形) of a verb produces the positive imperative (command). This is quite easy to mix up with usage 3. It may help to understand that the な in this case is actually an abbreviation of なさい. I'm not certain how formal this sounds to a native.
食べ｛たべ｝な! - Eat it!
行き｛いき｝な! - Go! (Get out!)
The unabbreviated versions are:
食べなさい。 - Please eat it.
行きなさい。 - Please go.
5. Expressing the concept of wonder (～かな)
Lastly, when a sentence is followed by かな it expresses the speakers sense of uncertainty about how something became the way it is. This is usually translated as "I wonder how..." or "I wonder if..." in English.
おいしいかな。 - I wonder if it's tasty. (I wonder if it's any good.)
Hope this helps. If I missed anything or am incorrect, please point it out in the comments.