If you had a field DateTimeField1 and wanted to display the following year in DateTimeField2, you could do the following in JavaScript;
var d1 = util.scand("yyyy-mm-dd", DateTimeField1.rawValue);
if (d1 !== null)
{
d1.setFullYear(d1.getFullYear()+1);
DateTimeField2.rawValue = util.printd("yyyy-mm-dd", d1);
}
Good luck
Bruce