Is it obligatory to repeat ablution and sprinkle water on clothes upon feeling a drop or two of urine discharge after performing istinja and moving around?

If you are certain that urine has exited after performing ablution, you must repeat the ablution because it is invalidated by urine. You also need to wash the clothes that have been soiled by urine or change them; sprinkling water will not suffice here.

If you are unsure whether urine has soiled your clothes, then sprinkling them with water is sufficient, along with repeating istinja (cleaning oneself after relieving nature). However, if your feeling of urine drops exiting is merely a doubt, the preponderant opinion is that doubt is not considered after ascertaining purity. You should disregard this doubt, and it is possible that obsessive whispering (waswas) plays a role in this matter.