What to say to her?

i had this mad chemistry with this girl at one stage earlier in the year, but it all died off when we kissed at a party.

Since then we have spoken but it hasn't been the same. I didn't think much of it but have only just realized I like her a fair bit.

I have one class of school left with her, forever. I just want something to say to her that might be able to initiate something or else I may not ever see her again.

Is this something I should just let go?

Thanks