How to force the maven to redownload all the packages ?

First Way: 

You can use mvn option -U : which forces the maven to download the dependency into local repository (.m2 folder)

Eg:

mvn clean package -U

Second Way:

Use purge-local-repository

Eg:

mvn dependency:purge-local-repository clean package

Third Way:

You can manually directly delete the .m2 folder in computers home directory (like in linux - mac, ~)