Yes, you can upgrade your 1.x license at a very convenient price, or if you purchased HighDesign 1.8 after January 1, 2014, you can upgrade to HIghDesign 2015 for free. Available upgrades are Standard 1.8 to Standard 2015, Pro 1.8 to Pro 2015, and Standard 1.8 to Pro 2015.
You can verify your license and proceed to the upgrade directly from within HighDesign 2015. See this page
for detailed information.