If you didn't use a package manager, there is no way to upgrade automaticly. You can do a make again, which will overwrite existing files. This will very likely work, but it's better to use the dpkg package manager. What you can do is the following: unpack the source file and use
mkdir build
cd build
cmake ..
make install `pwd`/install
This will install Hiawatha in a subdirectory named 'install'. Look inside that directory to see what files are created at the root of your system via 'make install'. Remove those from your system. To create Debian package, simply execute the script extra/make_debian_package.