Is this the same club you asked about here? If so, you received some very good advice in that thread.
It looks that you have participated in several activities throughout high school, (Operation Smile (leadership position), MUN, recycling club, CHKD circle group (leadership position), working, swimming x 4 yrs, lacrosse x4 yrs, volleyball x 3 yrs, as well as honor societies). If you had no activities through high school it might be different but, with a list like that, no school is going to scrutinize the fact that you added another activity junior year.