Welcome to the forum.
If you're not seeing problems with power, economy or the amount of smoke out the back then I'd say your injectors are probably fine. You probably don't even need to worry about cleaning the injectors.
That said, you can run some injector cleaner (buy it at Supercheap, Repco, Autobahn etc) through the thing - this can cause a problem though, and if it does it's something you might want to know about. If varnish/deposits have formed over small worn areas of the injectors so that the injectors are within spec again, using a cleaner may remove that and cause you to use a lot more fuel and blow a lot of (black) smoke. This is a sign that your injectors were worn out, and only functioning normally because of the deposits left on them.
You could just leave it. Personally I'd have the injectors removed and checked by a diesel mechanic. They'd be able to tell you whether or not the injectors had any issues.