I am looking for a positive synonym for the word sacrifice. Something that highlights the positive qualities needed to sacrifice the old and go with the new.
"Trade up" and "modernize", within certain contexts address the concept of replacing old with new but they do not express any pain associated with that exchange. The best word I can think of is your subject word, "sacrifice", used in conjunction with another word or two to make a very clear expression such as:
"Sacrificing familiarity for speed and added functionality"
"Giving up his __ for a newer model was a small price to pay"