well, since the chips are supposed to stay firm and not spread out, you would need them to be firmer (at least when mixing).
You might try making, not quite sure if it has another name, but peanut butter filling - I recall mixing with powdered sugar, and sometimes a bit of cornstarch or butter, or once in a while brown sugar (though that would melt easier, it tasted good) for a stiff pale peanut butter putty that can act as layers in other sweets, or to approximate the peanut butter filling in chocolates, or other kinds of peanut butter fudge or candy (buckeyes, or whatever). It is just to dry the peanut paste out a bit. Since you're also going to be baking these in blondies, I suppose adding a bit of flour could also work - you just wouldn't want the taste if the flour was uncooked. It can be chilled if still a bit soft, chopped into chunks, and added to your recipe, and any remainder should be kept refrigerated and used quickly.
Or, you could go the other way and try something with more fats - coconut oil or cocoa butter, because they're solid at room temperature. The pb chips are supposed to be similar to chocolate chips (fine starchy cocoa powder emulsified in cocoa butter), so you would use a solid fat to firm them up at room temperature, but they would melt, rather then dry up, at higher temps. I think I've seen some recipes for pb chips on this same principle, for those who want to make their own because of dietary restrictions. Again, you would likely need to chill until firm before chopping into chunks, and refrigerate the remainder.
(ah, found some recipes along the same lines).
To substitute with two cups of pb chips, you would want two cups of your finished product - though how much peanut butter you start with will depend on how much of which other ingredients you're adding, so I couldn't say - but likely a cup and a half of peanut butter will get above two cups worth of chips/filling, considering how much it will need to be thickened to be made solid.