This is an extremely difficult subject and will probably depend a great deal on your situation, and you have given very few details. For some discussion of this subject, you can read this article:
Global/Worldwide Cost of Living Survey Rankings 2007/2008, Cities, International, Europe, Asia, America, US, American, Americas, United States, Africa, Australia, USA, Asian, Canada, Expensive, Cheap, : Finfacts Ireland
But you can not simply multiply a percentage times your current salary and believe you will come out even. You will need to look into more details.
For example are you single or will you come with a partner? Do you have children? Will your children go to private school or public school? What about taxes? etc, etc
Further Zurich, Switzerland is an extremely expensive city, probably the most expensive in Switzerland. If you will live elsewhere (Lausanne for example), you will notice a dramatic difference in cost.
In addition, I am confused about why you are discussing Euro when the currency of Switzerland is the Swiss Franc. The exchange rate is nearly equal with the US Dollar, but I would not think that if you earned Sfr 115K that you would have equal purchasing power.
I would start by trying to estimate the big ticket items (Rent, School, Health Care, Tax, Trips back home, Transportation, Food, etc) and make sure your new salary is going to cover it and leave as much left over for savings as you currently do. Here is a discussion in expatforum that takes this approach:
Cost of living table
Have an agreement with your boss that if, after 6 months, you find that you have made a large error in your estimation that there will be an adjustment.