UKC

I have an old waterproof pack (Arc'teryx Arrakis) that has glued attachment points made of soft plastic that have begun to come unstuck from the backpack material. The pack is made from Arc'teryx's oldschool AC2 a nylon ripstop which has a urethane coating on the outside and TPU waterproofing coat on the inside.

Does anyone have a recommendation for a glue that will bond soft plastic to urethane without curing too rigid? 

Currently looking at two part glues used for repairing rubber boats or a cyanoacrylate glue for porous material (permalock) that requires a spary activator to work.

I don't mind experimenting but high quality glues are expensive things and tricky to get hold of so any help greatly appreciated.

We use polymarine for hypalon repairs at work which is good, I think they do a PU version. There is a shop that sells it on eBay and they're quite helpful, might be worth asking them. I'd be tempted to try a flexible PU adhesive like sikaflex, tigerseal or stixall which is cheap and less particular about temperature or ratios of activator. Are the attachment points definitely glued and not heat or frequency welded? If the latter then glueing will most likely not be as strong. Can you mechanically fix it with a rivet or sewing in addition to gluing?

Yeah, some grade of Sikaflex occurred to me, too.