Language selection on multisite based on visitor's latest choice (cookie)

Hi,

I’m creating a multisite that contains 3 different blogs (English, Czech and Slovak) and it uses own subdomain (/en /sk and /cz) for each one of them.

So far I’ve managed to prepare a language selector that’s able to get browser language and then automatically redirect visitor to appropriate site. For this purpose I’m just using Multisite Language Switcher plugin.

Now I need to enhance it – by finding some way of how to remember user’s latest language choice for its using in the next visit, perhaps using cookies. Should I customize funcions.php and header.php somehow? or is there some plugin with such a funcitionality available. Thanks for any help or suggestions!