Codicil or new will?

I doubt the attorney is trying to drum up more work.  You don't say why the attorney advised you to execute a new will rather than amending the existing will by codicil, but I can think of a couple of reasons.  Perhaps you've had changes in your life that require a review of your estate plan.  Or, although I doubt there are any discrepancies between the law in Pennsylvania and in Massachusetts, it can't hurt to execute a new will with all formalities required under MA law.  Finally, because a codicil does not replace your entire will (only the parts you want amended), the attorney may be concerned she will create some inconsistency in the two documents that she and you overlooked.  In other words, tucked away in another part of your will may some language that was based on the portion of the will you are amending and which, after you execute the codicil, may be inconsistent with that new document.

Bottom line:  The attorney will have to draft and execute a codicil with the same care and attention to Massachusetts law that she would use if she were creating a new will.  For that reason, I doubt that an entire new will will cost that much more than the codicil.  Good luck.