This is the process I use for installing a new Julia version: Transitioning from Ubuntu PPA to official binaries - #2 by rdeits
If you are only changing patch versions (e.g. from 1.2.3 to 1.2.4), then your packages will be unchanged, and you don’t need to do anything. If you are installing a new minor version (e.g. from 1.2 to 1.3) then your packages will not carry over. But it should be easy to use the package manager to ensure that you get the same set of packages in the new version that you had before.
For example, if you had Julia 1.2 installed, and you then added Julia 1.3, you could do:
cp ~/.julia/environments/v1.2 ~/.julia/environments/v1.3
and then launch Julia and do:
pkg> instantiate
This will tell the package manager to install the same set of packages in Julia 1.3 that you had in Julia 1.2. For most cases that should be sufficient to ensure that your new Julia version has the same package environment that your old Julia version did.