Good news! You are eligible for a one-year recertification window under the new program. This means that from program launch (October 1, 2018) through October 1, 2019, you have two options for recertification:
1) Register for the highest level exam you held as a V6.x Certification (no prerequisites necessary).
2) Complete the prerequisite coursework and register for the next-level exam, moving beyond the highest V6.x certification you held.
Here’s what it looks like in practice (see pdf for reference):
V6.x Splunk Certified User is eligible for Splunk Core Certified User or Splunk Core Certified Power User.
V6.x Splunk Certified Power User is eligible for Splunk Core Certified Power User or Splunk Enterprise Certified Admin.
As you say the exam is not listed, maybe, check with email@example.com
All the best for your exams. (* As you are new member here, you can upvote any answers and if an answer resolved your query, please mark it as the "accepted answer" *)