Hello,
Register your product on your Arturia account, then the latest update for your version should be available in Arturia Software Center (ASC).
The last available version for JUP-V2 is version 2.7.0.76.
In generel the latest version you have license to will show in ASC.
Or go here:
https://www.arturia.com/support/downloads&manuals - Select JUP-8 V4, then you see the installer. If you need versions you can't see, then click the SHOW ARCHIVES button.
FYI: JUP-8 V4 is a total rebuild with it's own preset format, and it has a better sound emulation, but no dual mode.
Also JUP-8 V2 does'nt have a preset browser. Jup-8 V2 can't be used in newer Analog Labs.
I can confirm you don't own JUP-8 V4 with a JUP-8 V2 license.
Jup-8 V2 was originally validated by e-licenser. I'm not sure if that will mean you have anything in your case. But perhaps you need to ask Arturia support about that. I assume there will be no issues to the new ASC registration, if your documentation of ownership is in order.
JUP-8 V2 has'nt been maintained since Jup-8 V3 arrived. It's a legacy product.