This works for ongoing spells.
The Psychic Strike ability has 2 conditions that musmust be satisfied:
- you deal damage with a sorcerer spell
- that spell expended a spell slot
So any time you deal damage with any sorcerer spell of 1st level higher that you cast by expending a spell slot, you meet the conditions for using Psychic Strike (as long as you haven't already used Psychic Strike this turn).