I played my first game last night on the Table Top Simulator (great mod, go get it). I had a few situations where the number of rerolls didnt match the dice, do these rerolls carry over?

As an example, rolled 3 dice with depleted storm troopers that had an aim token plus their inbuilt precise. Rolled 2 hits and a miss, spent the aim token. Does that allow me to reroll the miss dice up to 3 times until I get the result I am after, or do the extra rerolls get lost as I can only spend them on one dice?

The rerolls do not carry over. You would have to spend another aim token to reroll the same dice again.

RRG pg. 13, second-to-last bullet point under "Aim" heading:

A unit can reroll the same die multiple times by spending
multiple aim tokens; however, each die can only be rerolled
once per aim token.

so with @Thornoo1s example he could re-roll the miss from precise, and then if he gets another miss spend the aim token to re-re-roll it?

36 minutes ago, slasher956 said:

so with @Thornoo1s example he could re-roll the miss from precise, and then if he gets another miss spend the aim token to re-re-roll it?

Nope, precise isn't it's own reroll, it boosts the effect of an aim token.
He rolls 3 dice and gets all blanks.

Spends the aim token to re-roll 3 dice. 2 from the token and +1 from Precise.
Regardless of the new results, if he wants to reroll again, another Aim token would have to be spent