When Poles go abroad they continue speaking Polish, but their children don't always continue with polish customs/traditions.
It can be difficult to keep a language going. It can all depend on circumstances.
If there are very few people in a particular area speaking that language then there are few opportunities to use it.
Also kids most probably feel if no one else (in my English school) is learning the language then why should I bother.
Some get help from the kids' grandparents, looking after them etc.
I was born in the UK and I was lucky in that I lived in an area with many Poles who got together to provide a Polish School on Saturday mornings.
My Polish isn't brilliant but I get by in most cases. The other day I even managed to help a Pole who did not know English well enough yet to fill out an English school application form for their child.
When I had kids I started to brush up on my Polish and I now send them to a Polish Satuday School not far from us.
They are not too happy about going, but they still go. (I don't feel too bad about sending them as I know that they would otherwise be playing computer games)
If I had not had kids I guess I most probably would have lost most of the language, as it is I speak to them in Polish every day and I also meet more Poles (mostly other kids' parents) then I would have done.
I also try to go to Poland at least every other year, mostly to visit relatives. (Its lucky for me that the UK is not too far from Poland)
My wife is English, she has helped a lot and is happy that the kids are learning Polish. If she had not supported me it would have been a lot harder.
I try to keep up the Polish traditions like Wigilia and make pierogi (or at least my wife makes them with me and the kids helping)
Good luck to anyone learning Polish, trying to keep their Polish going or even trying to get there kids to learn Polish!