Should I switch research subfields to get a paper to increase my chances of getting in to grad school?

I am an undergraduate physics student at a middling state university. My goal is to get into a good grad school for theory (no preference as to which subfield), so I obviously need to do as much research as possible (publish as many papers as possible, since I haven't published anything yet). Thus, last school year, I did research in a group in a subfield that my school is well known for, and I had a well-known professor as my supervisor. Unfortunately, I accidentally overwhelmed myself with classwork, resulting in my research performance being subpar. Furthermore, the nature of the field is such that it takes a long time to gain the requisite skills to even contribute in any meaningful way to papers (I know all areas are like this, but this is even more so).

Should I continue to do research in this group this year and try and fix my mistakes, or should I switch into a different research area with a higher probability of getting a paper?

Also, if I do decide to switch, would grad schools count it against me that I did research for a professor for a year and didn't get a recommendation letter from them?