How to substitute peanut butter for peanut butter chips
You cannot convert it, because they are two different ingredients. 

Peanut butter chips are pieces which stay whole when baked. They don't melt, just sit there so you can bite on them after the cookie is baked. 

Peanut butter is a creamy substance, and if you try to put it in a blondie, it will not form a chunk, it will become part of the dough, giving it a completely different texture and maybe even hindering its baking well. Even if it bakes properly, you will get a totally different result, with dough that tastes uniformly of peanuts, without a contrast taste to bite on. 

You could try putting in whole peanuts (shelled, without the papery skin, but unsalted and toasted), in which case you can use the same amount in cups. It will still be somewhat different, because they will be harder to bite on than the chips, and it can make the blondies drier as a whole.