You can get matching yarn and crochet a patch into the area. I'm afraid the knit fusible would peel back on the edges and irritate your elbow and deposit fusible particles inside the yarn. Can you use a coordinating piece of woven fabric and zig-zag two symmetrical patches on both sides to completely cover? You could use some type of decorative fabric for that. Otherwise, re-darning is no crime. You can just keep doing it as long as you like. Eventually you'll get into areas of the sweater that don't get as much wear, so the darns will hold if you go out far enough.

If you go with new cardigans, Lands' End has some great traditional options in stock as does on occasion Banana Republic.

I don't know how to crochet or knit, so that option is out for me. Many family skills were passed down, but not those. Thanks for the idea, though.

I will still have to re-darn the new holes but hoped there was some way to slow down the progression.

I will try to think of something else.

suede (suede-like?) patches for elbow of jackets and sweaters

https://www.wish.com/product/5c355914c7d0216873ecfe92?hide_login_modal=true&from_ad=goog_shopping&_display_country_code=US&_force_currency_code=USD&pid=googleadwords_int&c=%7BcampaignId%7D&ad_cid=5c355914c7d0216873ecfe92&ad_cc=US&ad_curr=USD&ad_price=1.95&campaign_id=7203534630&gclid=EAIaIQobChMIi8vzhdT56AIVjbbICh0ovwGOEAQYAyABEgIdi_D_BwE&share=web

I made ultrasuede patches for a previous sweater. Not iron on, I hand stitched them on. I found the stitches pulled the knit more and I got more small holes around the edges.

So I think if I do go the patching route, I need to find something that stretches. Maybe apply from the inside ?