Advice/opinions needed

[alexspantry]

I am currently in the process of renovating our living room. We have recently ripped up the old carpet to get down to the bare floorboards underneath the carpet, underlay and vintage lino that was down to discover a massive slope down towards my exterior wall. The majority of the floor is level which is ideal ready for the new SPC/LVT flooring to go down but we have an issue. Approx. 1 metre from the exterior wall we have a slope down, we lose about 38mm (1 ½ inch) drop. I've climbed down under the floorboards into the crawlspace below and the joists are solid (no damp or damage) they are just installed lower that the others in the room. I am looking for suggestions on how to "raise" the dropped part of the floor so it's level with the rest of the floor, hopefully without having to rip off the skirting board, jack up the old joists and prop them up with supports. If there are any suggestions, please I'm all ears. Thanks