Detailed Instructions: Given a travel related situation, and given a specific question about the situation, summarize the question into a title
Problem:I live in Canada with a German passport and a student visa. From a recent climbing trip to the US I still have this green I94-W form in my passport. I didn't surrender it on leaving the US back to Canada, because I expected to come back for another climbing trip relatively soon.

That trip got postponed a few times, and now the situation is that the I94-W would expire while I'm on the trip. That is, it would still be valid on entry, but not on exit.

Can I apply for a new I94-W at the border crossing, or can these Visa waivers not be extended back-to-back?

Solution:
Extending an expiring I-94W, land based entry to US