I just really started flying United about 2 years ago so I'm still learning the nuances of United. I have some questions, please, to help avoid missing an int'l connection in a few weeks. I'm booked in Polaris from LGA-IAD-SFO-XXX. The flight from LGA-IAD is late nearly everyday and I have a 1:04 layover. IF it is the case on the day of travel that the LGA-IAD flight is delayed, then I may miss my IAD-SFO flight which means I'll miss the int'l connection. I've been trying to be proactive about this by trying to pick a new routing out of LGA but every option involves an exorbitant fee (think $2000 or so) b/c it will re-price the entire ticket. So my questions are:
1) is there ANYTHING I can do in advance to get a new routing AND avoid a crazy change in ticket price?
2) will I have an option to change anything for free within 24 hours of travel assuming there are no weather waivers or anything in place? I mean are there any "24 hour change rules" that I can apply on the day prior to travel?
3) IF there is an irrop on the day of travel, will United let me co-terminal to EWR for better choices to get to SFO so I don't mis-connect?
In the meantime I'm REALLY hoping for a schedule change! and thank you as always for reading and for any useful replies. Thank you all and safe travels!

1 - No; repricing your entire itinerary is standard in this case.
2 - Your profile lists United Silver, so you should have the option to make a same-day confirmed change beginning 24 hours prior to your departure from LGA. This requires availability in your current fare class, however. You could also stand by for an earlier LGA-IAD flight.
3 - Yes, but probably not until the LGA-IAD flight is absolutely hopeless, and you�d have to get yourself to EWR.

3) If there are day-of irrops, you can also ask to be rebooked on something like JFK-HND-XXX on NH.

You can just go stanby for an earlier LGA to IAD flight. I did that recently out of DTW to EWR. I had a tight 2 hr. EWR connection to international so the day of departure I had United put me on the stanby list for an earlier DTW to EWR flight and I got on. I was glad I did as my original 2 hr. connection flight was delayed.

It was really annoying to be put on the stanby list at United though. I could not do it using their app or Kiosk as they advertise. I asked at checkin and the agent at DTW said she couldn't do that and just seemed lazy so then I had to call. She had time to just stand there while no one else was even at the desk that time of day to checkin.

It took the agent on the phone 45 minutes to not be able to help because she said the flight was full and thought it was a partner flight which was totally wrong. It was on United. I advocated to have her still put me on this stanby list even if it was "full" as things change and open up. She just had no idea how to so made up excuses. The agents are not the most helpful at United. Then I had to go ask again at the DTW checkin desk and some guy finally helped to get me on the list, where the other agent refused to help. It took him two minutes to do this simple task. I got on the earlier flight.

I would either change at 24 hours or request to get on the stanby list for an earlier flight to IAD. One hour connections can be a huge issue at United. I try to book 4 hour plus connections for international now on United with all their problems, poor customer service and bad IRROPS response.

When I can't book these types of connections I try to move up on flights with stanby or use the 24 hr. change.