Can a witch take improved familiar, and if he/she can does the new familiar know all the old spells, or just the default 2 per level and patron spells?
Can a witch take improved familiar, and if he/she can does the new familiar know all the old spells, or just the default 2 per level and patron spells?
It's not explicitly stated that your new Familiar holds the same spells as the old one, but frankly it would be rather silly if it didn't.
So ask your GM.
If a familiar belongs to a witch that has died, it only retains its knowledge of spells for 24 hours, during which time it is possible to coerce or bribe the familiar into teaching its spells to another, subject to GM discretion.
Now, if you dismiss your familiar, you didn't die. But does the dismissed familiar also retain the spells in its knowledge for 24 hours? I think that would be cool.
You could explain it as your old, dismissed familiar taught all your spells to your new, Improved familiar.
Basically this is just an IC way to explain how the spells transfer over, accepting that the do from Sean's post.