A lot of posts on forums deal about difficulties in upgrading from an older to a newer version of Linux. Compared to that, problems posted for installing Linux are much lesser. While, with due regard to people who have made elaborate infrastructure for upgrading, the question is, "Why upgrade, when you can simply re-install?". Here, I will put forward some points, which I believe, can throw some light on the matter. While re-install looks like a "brute force" approach, it is not all that bad.
First, you must have planned for it. That is, your user data should be on a separate partition. That is /home should be a separate partition. When you install Linux, you can opt for manual partitioning and keep the partitions the same as before. Be careful to not to format the /home partition. That way all the user files will be preserved during a re-install of Linux system.
What are the advantages? First, there is a slight vagueness about upgrade. You are not sure whether all files have been correctly put in proper places. With re-install, there is a kind of "clean-up" and you are 100% sure that proper files are in proper places. Upgrade takes a lot of time, because it has to upgrade all the packages. Re-install is much faster. After re-install you can install the packages of your choice either manually or via a script.
What about data in root partition? A s a matter of principle, all data of interest should be clearly identified and backed up. So you should have a backup script to back it up. The same applies for any programs in root partition.
To sum up, re-install offers a good way to "clean-up" your system periodically and make it up to date. Re-install should give you a much more reliable and efficient system.