Elliptic Curve Cryptography

i have a base point called G i add this point to itself a number of times called xTimes (is is a finite field) so, the result is mod by a number called n the result point is K ----- now i have point K i want to change the mod number (n) to another number now i want to get the new point K -- inputs: base point G in known xTimes is unknown K is known old mod n is known new old mod n is known we need to know the new point K note: old point K - (G * xTimes) = 0 new point K - (G * xTimes) = 0 also you also can change the old G to any new G as you want to make the correct results i want C# code (or any), or even a formula i can test it.