Disassemble, clean, rebuild and lube everything you know how to do. If there is very obvious wear in something inexpensive and you can get it today, replace it. Otherwise, just put it all back together, make sure everything is adjusted correctly and ride it.
If you are having problems with something and you can't adjust it out, then consider if it's worn and needs replacing.
If you are going to replace worn things that are not currently giving you problems, then you may as well just replace the whole bike.
Last edited by Iride01; 07-18-19 at 09:45 AM.