In the Baltic languages, 'las' is 'wood' or 'forest', so a name starting with 'las' would probably mean 'son of the forest'.
That Ancestry.com link is interesting, as it takes the origin right back to the Slavic where it belongs: "from a form of the personal name Ladislav (of Slavic origin)"
The 'las' comes from my research of our name, Lasevicius, which is Lithuanian, apparently having a strong Polish root. It's origins are a mystery, but the 'las' meaning has been confirmed for us.
Having said all that, the Germans did go into the Baltic territories, so there may well have been a mixing of blood there.
~ When in doubt, just take the next small step ~