There’s no way to tell for sure with out stripping the fork down. I’ve got 3sets of pre 2012 Reba’s , two can be increased to 115/120 and one can’t. The one that can’t is aftermarket the other two are oem.
Stripping the fork is easy, have a look on SRAMs you tube channel as they have some good videos on there of how to do it. IMO the most difficult part of the strip down is getting the circip out of the bottom of the satanction so that the air chamber can be disassembled.