The need of communication doesn't mean you should stalk them endlessly and become obsessive.
This means you talk with them casually as friends (if possible).
You can bring up the fact that you'd like to get back together.
Before you do that, you need to clear the air of anything negative.
First, make sure you've apologized for anything you've done wrong.
If it was them who did something wrong, think long and hard if it's worth dwelling on it.
If it is, you might want to rethink your strategy all together.
Staying together means, nothing was worth your separation.
If it was minor, try to let it go.
Over reacting or going back to the same horrible time can ruin your relationship, and hopefully yours is worth more than that.
The goal is to stay as care-free and easy going as possible about this.
There are numerous ways to converse, but make it a point not to be an annoyance.
This way, maybe you'll be on their mind as much as they've been on yours.
E-mail, phone conversations, and friendly get-togethers are all great.
In the beginning you'll want to keep these more light and airy.
Remember, the more positive vibes you send out, the better the situation will look to both of you.
There will come a point where you'll need, or want, to discuss getting back together, but that won't happen until you are both completely ready.
Don't jump in to anything you both aren't ready for.
Even if you are completely ready, that doesn't mean they are.