Take everything in this answer with a bag of salt, but I think she may re-run soon before the Sumeru region launches. We have Ayaka re-run, and Yoimiya may get a re-run before new characters are introduced in the Sumeru region. You should keep yourself up-to-date with official game sources, and if they announce that Yoimiya may get a re-run, I'd suggest you start saving up primogems.