Have you ever heard of an
SRS? They're good for learning new things and reviewing things you already know, but may not have come across in a while. I'd say to use one. Anki seems to be pretty popular for Japanese, and it comes with the James Heisig book 1 cards already loaded in it. I use sentences with mine, ala
Khatzumoto, as I find learning words in context is helpful for being able to use them.
If you need reading practice you can go to
Wikipedia and pick anything you want to read about. It's nice in that headwords pretty much always have the readings written after them, so if you see a word that is a hyperlink and you don't know how to read it, you can just click on it and get the reading. Oh, and if you want to read about something in Japanese and don't know what it's called, you can just type it into the English version and then look for 日本語 under "languages" on the left side of the page, and it'll take you to the Japanese page if there is one. There isn't always, but I've found that the topics that don't have Japanese pages are pretty specific to some other country, or just in some way not all that relevant to Japan.
For listening and reading practice at the same time (or separately, however you want to do it), there's
ANN News, from Asahi TV. It's great in that you can watch the video and follow along with the text, which is an exact match to what they're saying the vast majority of the time. All you need is Windows Media Player or Real Player and some speakers.
So, there you have it. That's pretty much how I keep up my Japanese. You could also try to look for some message boards on some topic that you're interested in to read through: that way you'll develop a good knowledge of the terms used in that field or area, along with getting some conversational practice, which will lead you to being able to talk about it with people. Hope this helps!