It would be gerat if there is global settings for alle jobs to set one url for the redmine installation and a regular expression how redmine projectname shall be guessed from jenkins job name.
E.g
redmine url: https://redmine.myserver.com/
redmine project name: .for(.)

If job name is "myjob for redmine project", the redmine project var would be set to "redmine project" automatically for this job.