wp_get_archives() advanced features

Hello.
I am using wp_get_archives() to list my posts, but I need to do it in a bit advanced way… I need to display 15 first words from each post. So lets say I use wp_get_archives(‘type=postbypost’) and it displays like this:

My first day.
My second day.
My third day.

I need to get it done this way:

My first day.
Today I went to school and ate some banana…
My second day.
Today I was sick and went nowhere except to the bed…
My third day.
Today I forgot what I did as yesterday I was drunk…

Does any1 know how to alter the code or maybe there is some plugin, that I don’t know?

Thanks a lot in advance!

Modestas