Lilia used to have language skills that changed with the season: in late summer, after 4 weeks in Algeria, her Arabic would be really good, but because I normally wouldn't come, her German would go down. Around Christmas, after a visit to Hamburg, her German would be great but Arabic would slowly fade.
We have now found the solution to this and it is called skype.
Lilia is now talking with her grandparents at least once a day, and while she was staying in Algeria, I spoke with her twice a day. She can now perfect one language while sustaining the other.
It doesn't have to be skype, of course. Any VOIP solution will do. The point is: being able to communicate across the world for free enables her to practice all her languages wherever she is.
You've got to love the Internet.