Should I lift the restraining order?

Your sister is not yet ready for a second chance. Until she has a long period of sobriety behind her, she needs to be handled by professionals who have both the tools and the professional distance to do so effectively. Trust me, it is in her best interest to release her for now. Do both of you a favor and say no. After she has been straightened up for a period of time, ask her to give her counselor permission to speak with you (if she doesn't have one, that's a definite no). Let the counselor make the call as to whether or not she's ready. For now, back off.