Same UI for different navbars with different data frames


I created a shiny app for my hospital, plotting several operating figures for the year 2018 compared with 2017. Among them are number of patients, reimbursement, operations, operating time etc. for the hole hospital and by department displayed in several tabs.
Now year has changed and I want to open a second navbar displaying the same plots, but with data from 2019 compared to 2018. Same UI but different data. The data are from three .csv-files
Functions for calculation and plotting are outsourced to "function.R."
What is the best way to reuse as much code as possible ?