Teenage dog (14 months) - "forgetting" known cues

How do we work this phase? In the past I haven't had issues with dogs forgetting words and behaviours. But the puppy lapsed in knowing what down meant for two weeks.

She'll be 14 months next week. She really struggled with scent detection last week too (ok with containers, had problems with room search). Should I just stick to known behaviours and easy cues? I'd like to keep with the scent detection (we usually do twice a week, and I can pivot back to containers if room searches are too hard) and weave pole training going. I guess, I just want to know if she's able to learn new stuff or not?