I’ve noticed after a couple longer days of riding on my dt2 that my clutch will get creaky, when I pull in the lever, and also seems to get pretty bad fade. The hotter the bike gets the softer the clutch pull feels. Wondering if my springs are tired, I replaced fibers, cleaned the steels and have fresh oil in it and still it behaves the same. 

wonder if I do go with stiffer springs, if anyone knows what to look for, if some from a Blaster or RD or some other Yamaha would retro fit my clutch?

So is it actually slipping--revs rising but not accelerating. Long story ahead!! as it transpired.
I did have once on my DT250 about a "78 model where the plates used to swell up under hard forest riding where i was using the clutch continually.
It didn't slip or look like slipping but gave a lever full of nothing maybe dissengaging right back at the handlebar.
Leave it to cool & back to normal. I never did fix it as used it on the road after that so all good.
Come to think, it used to groan if i did a hard start in say a high gear, a very audible groan.
But wait there's more haha--i just remembered in recent times on my RT2 rat race bike i machined the basket to take some used plates out of something yamaha maybe my YZ465 but plate ears lined up but wouldn't clear the basket inside of the fingers--just!!.
So assembled & gave it heaps down the farm in a cultivated soft paddock & it went instant swollen through gearchanging under power. Lever back to the bar & not separating the plates. Didn't slip though.
So apart again & fitted my second old set from my 465 or 490 & worked perfect 100%.
Are alloy bonded fiber faced plates.
Anyway i can't recommend them as won't fit & i'm guessing as to their origin. The old hanging on the wall-trick.
Sorry very long life story about bugger all. {Plates swelling is my guess}.
Out of curiosity "what replacement plates have you used" & did you leave the pesky rubber rings out if fitted.
Might have to buy a better quality set of fibers.
Won't be spring in my opinion unless its slipping bad & has glazed up the plates.