czy to brzmi poprawnie? ;p

new school, new people, new life and the same Karoline

Dobrze.

Add a comma or a dash after life:
>new school, new people, new life, and the same Karoline

I can't conceive what we would do without you :)

Irony is cuter when brief and understated. Just drop the conceiving part.
A question mark to finish it up would be a nice touch too.

And you wouldn't neeed the smiley...