How to raise up the electrical outlet after putting up a backsplash​

There are outlet extenders. Go to the hardware store. They can help you

http://www.homedepot.com/p/Multi-Gang-Non-Metallic-Box-Extender-2-Pack-B1MGEXT-2/204222412

This isn't code in a lot of places, but it works and costs nothing.

Take out the top and bottom bolts that attach your outlet to the box. Pull out the outlet and wrap electrical tape around the edges where the electrical wires attach to the outlet (I do this every time I wire an outlet to guard against shocks if I touch the area and sparks if the connections touch the metal box.). Then insert the bolt through the outlet, add a nut of sufficient depth to the bolt (this is a little fiddly), then seat the bolt in the outlet box receiver hole and screw it in firmly. Repeat for the bottom hole in the outlet using a nut of the same thickness. The nuts are essentially spaces that will bring the outlet out the depth of the backsplash.

Check out this blog....http://thespacebetweenblog.net/the-secret-to-getting-your-outlets-to-sit-flush-with-the-outlet-cover/outlet-collage/

Sorry......spellcheck got me....... The nuts are essentially spacers that will bring the outlet out the depth of the backsplash. Hope this helps.