Then you didn't really remember the vocabulary, did you? It's critical to remember the tone along with the words. I know it feels like you "almost" got it, but if you don't remember the tone then you should treat it as not remembering the word at all, IMO.
FWIW, what helped me was doing a little finger gesture in the air with the syllable, sort of tracing the pinyin tone marker. Then when I talk I'm sort of habitually waving my finger down out of sight, but at least I'm producing the sounds correctly. Basically, treat learning vocabulary as learning {syllable, tone} tuples, rather than trying to learn a syllable with a built-in tone.
Then you didn't really remember the vocabulary, did you? It's critical to remember the tone along with the words. I know it feels like you "almost" got it, but if you don't remember the tone then you should treat it as not remembering the word at all, IMO.
FWIW, what helped me was doing a little finger gesture in the air with the syllable, sort of tracing the pinyin tone marker. Then when I talk I'm sort of habitually waving my finger down out of sight, but at least I'm producing the sounds correctly. Basically, treat learning vocabulary as learning {syllable, tone} tuples, rather than trying to learn a syllable with a built-in tone.