Is it possible to make it so everytime I browse to a certain site it changes a certain part of the url? Examples inside

The reason I want to do this is for reddit. I hate the new design and sometimes I just want to type: reddit.com/r/insert whatever here.
But can I use anything that will always change : reddit.com www.reddit.com to old.reddit.com BUT as well only change those two parts but always reinsert any /r/subreddit part of the url untouched?
I know how to redirect if im ONLY typing reddit.com but was hoping you guys could help with a solution for this.

Solved thanks /u/BaconEatingChamp I'm dumb!

Thanks!