Hello @JohnManchester ,
You can't autonomously extract contents from an IPE file (that I wrote on the thread you cited)...switch does it for you during the update/upgrade process. It's the Comware 7 magic which step in.
When an IPE file is used (it means you're working in a Comware 7 environment) it could embed both System Software and BootROM when necessary...and the update procedure takes care of managing both ones if required (e.g. update the BootROM if required/necessary).
To stay on the safe side, if I were you, I would to look for a software release that offer the BootROM version 147 and then use that one as an interim software build - you can consider this build that way - between your actual software build - R3113 P05 of June 2016 - and the latest you want to reach, the R3208 P16 of April 2019.
Think of it as a sort of "stepped upgrade process".
In ANY case you should carefully read the relevant Release Notes to understand what are restrictions and requirements (remeber you're moving from an old build of the R31 software line to the newest build released of the R32 software line).
If you look at Release Notes (here), you will discover that R3208P03 (January 2018) will bring you BootROM 147...so I guess that your upgrade path would be R3113 P05 -> R3208 P03 -> R3208 P16...consider that staying on the R31 software line is a dead end (latest is R3116 P05 of September 2017).