sketchup_application_helper.rb

module SketchupApplicationHelper
  def self.path
    Sketchup.find_support_file('sketchup.exe')
  end
  
  def self.start
    # Need quotation marks around path as it contains spaces.
    pid = Process.spawn("\"#{path}\"")
    Process.detach(pid)
  end
  
  def self.restart
    start
    Sketchup.quit
  end
end

SketchupApplicationHelper.restart