Repair vs replace my Trek 1.5
I would always repair a bike unless its crash damaged. 

Since it sounds like you ride then put away the wet/dirty bike, this has been more of a gradual decline rather than sudden damage.


Remove the wheels from the bike, and remove the tubes/tyres/rim tape.
Fill a container with warm soapy water - pick a container you can put 60 degrees of rim into.
Clean your rim with a dish brush or perhaps light steel wool - may need to soak each bit then scrub.  Clean rim around and between spoke nipples too.  Also clean up the spokes while you're there.  Avoid getting a lot of water in the axle bearings.
Then true your wheel using the bike as a frame.  This will require a spoke key - its very hard to do without the right tool.  Aim is to get the wheel flat.   Then refit the tyre and tube and remount in bike.
Finally tweak and adjust the brakes.


If you are looking for an excuse to buy a new bike and can afford it, then go for it.  No need to seek justification from random people on the internet.