How to stop current iteration of loops in navision

There BREAK command which would let you break out of the loop does not exist as a separate command in C/AL, but you can code around it:

FOR i := 1 TO 100 DO BEGIN
 // option 1:
 IF MyExitCondition = TRUE THEN
   EXIT; //this exits the function, not only the loop. so be careful
 // option 2:
 IF MyExitCondition  THEN
   i := 101; //code after this statement will still be executed, but not then next loop iteration
END;

For REPEAT ... UNTIL loop you can use something like this:

If aRec.FINDSET THEN
REPEAT
  IF MyExitCondition THEN
    EndOfLoop := TRUE;
  ELSE
    EndOfLoop := aRec.NEXT = 0
UNTIL EndOfLoop;

Third possible alternatie (although I don't recommend using it) is to put your code in a report based on the Integer table, let the report to do the looping and use CurrReport.BREAK.