You can! But you will have to rewash your jars. I'd put them through the dishwasher on a quick cycle (at the minimum) to get them clean, then reboil the jam to 220 °F and then transfer to jars and seal again.

You bring up an excellent point! The 220 °F set point is for those of us at sea level. I tried to do the math of how the set point would change at 3000 ft, and it seems that your set point would be closer to 214 °F.
If you are getting a good set when you boil your jams to 200 °F, then I'd go with that but my worry is when it comes to canning the jam safely. If you boil your closed jars to seal them, you need to increase the time they are in the canner to ensure they are "safe" for storage and consumption later. Here's a few references with more info on this topic:
- For the recommended time to process jars if you are boiling them to seal them: https://nchfp.uga.edu/how/general/selecting_correct_process_time.html
- This reference suggests increasing the processing time by 1 minute per 1000 ft of elevation https://nchfp.uga.edu/how/can_07/prep_jam_jelly.html
- This reference says to boil filled jars for 5 extra minutes at an altitude of 3000 ft https://extension.sdstate.edu/altitude-adjustments-home-canning.

Hi Irene,
You are correct! The setting point applies to jellies too!