This is an unsupported solution and assumes that everything you have done is in a Delivery Unit with defined project(s) and one or two schemas. I did not do an update to the existing server, I created a new instance and imported my rev 68 content to the new instance.
I created a new AWS instance using the new image on SPS7 (I actually used rev 70, but I saw that rev 72 is available now). While that instance was booting up, I exported my delivery unit with all my project development artifacts from the old system (using the File-Export-SAP HANA Content-Delivery Unit menu path), call this "du export".
After that completed, I also did a content export using File-Export-SAP HANA-Catalog Objects. Call this "data export".
When the new server came up and I had access, I reversed the process and did an import of the files created on the "du export" (File-Import-SAP HANA Content-Delivery Unit) and activated. Once I got through the activation phase, all my development objects were created but I had no data.
I then did an import (File-Import-SAP HANA-Catalog Objects) of the "data export" to bring in the catalog objects and data.
A few gotchas are still around -
1) if you enabled PAL, you will have to do that manually again using the correct scripts on the server. Not hard to do, but be sure to use the updated scripts on the new server to make sure that things are correct. There are also some naming conventions for the PAL algorithms that changed between 68 and 70 that I had to correct in my scripts
2) If you had a trust-store for a hdbhttpdest, you will have to recreate it manually
3) Check the roles/authorizations for your user(s).
You have to pay a few hours of double AWS time since you'll be running two instances, but it is one work-around that worked for me while I was waiting to get an upgrade to SPS7. You can even reassign the old EIP to the new instance, but i suggest doing a full new checkout of the objects that have loaded into a new workspace and project or you might run into development version issues (it seems that the change counter restarted once I imported the DU.)
Just remember to stop/terminate the "old" instance once you have verified everything on the "new" instance to avoid racking up extra costs.
Hope this helps.
Jim