Domain renewal/expiration date for european domains (whois)
Solution 1:
Most ccTLD (.de and .eu too) don't have expiration date shown when you run whois, while .sk is one of those that do. Only solution until this policy changes is to use api to get full whois from web interface on that national registry. Here you can find list with available whois info for most ccTLD: http://linuxmafia.com/pub/linux/network/domain-check-testdata
As you can see, most of ccTLD whois servers don't return expiration dates.