Hi,
This one is somewhat tricky. Live Watch has the go-to-definition command because the symbol files (where the variable list comes from) record the definitions of variables. So, the command works independently from the IntelliSense engine (and even for projects built outside VisualGDB). Finding all references requires properly parsing all source files, and this is done by a completely different part of VisualGDB.
That said, it’s still fairly straight-forward to achieve: you can go to the variable definition via Live Watch, right-click on it in code and select Find All References.