Sleep Training Again at 18 Months...is it possible?

My baby was sleep trained when she was 6 months old. We used the CIO method. Surprisingly, it only took us 1 night to sleep train her at bedtime. The nap took longer, which was a week. It continued on until she was 14 months old.

Gradually, she started having sleep associations again. The daycare transition, getting sick almost every month since starting daycare, teething, traveling, etc. During these times, I would bedshare with her because I knew she needed some extra soothing. When she felt better, she would just go back to sleeping in her crib with no problem at all. Until she started having late-night wakings. It gradually increased, so I started tapping her to sleep, holding her hand, etc. It worked for a while. But now at 18 months, it's the worst so far. She wakes up almost every hour looking for me. At times, she won't stop crying until I pick her up and we cosleep.

It's hard because I don't get anything done at night anymore unlike before. Also, her sleep quality is affected, which causes her overtiredness during the day. I dread bedtime now. I want to sleep train her again. Is it still possible at 18 months? My baby also has very challenging temperament which makes me hesitant to start sleep training again. Any advice is highly appreciated!