There isn't any one size fits all answer for this, so i suggest altering your sentences to use a different word each time.

For example

"I never stopped looking for you" = "my search for you was unending" (yahi fah hi lost unslaad)

"They will not stop" = "they will never rest" (nust fen neh praan)

"I cant stop him" = "i cannot defeat him" (zu'u nis viik rok)

"It feels like time has stopped" = "it is to me like time is unmoving" (nii los wah zuu med tiid los mulhaan)

Or any other variation you can think of. :)