So this isn't exactly a 'violin lesson' post. It's musical problems/lifestyle theme inclined. Something I suddenly felt an urge to write a quick note about - for myself and for you.
As the title suggests, I'm going to be briefly mentioning the problem with memory slips. And what you could do about it. Small and big ones.
Small ones:
Forgetting a passage during a live performance. Don't fret, avoid going over the passage again. Attempt to continue onto the next passage that you remember coming after it. If there's an accompaniment part, listen to it and try to sing the melodic line above it in your head.
Having a problem memorising a new piece of music. It's not about learning the notes. Sing the music in your head (or out loud even! Preferably in a room by yourself *cheeky smile*) and know it well from your heart, not your head. Discover interesting harmonic changes, rhythmic patterns, intertwining voices between solo parts (+ accompaniment part) and other notations by carefully examining the score.
Big ones:
Only remembering collective bars of pieces you learnt months/years ago. No one has perfect memory. So you have one option: revise! Just like you did in primary school and high school, look back at your music! Wipe off the dust, take the score back out of your shelf, and just look at it. I promise, without even having to lift your instrument to attempt playing it again, it will all come back to you. You might even remember the exact feelings you had when you performed the piece in a certain setting.