Occasional Deadlock

UPDATE AttendanceRoll
SET ErrorFlag = 0
WHERE ContractID = @ContractID
AND DATEPART(month,AttendanceDate) = DATEPART(month,@Month_Beginning)
AND DATEPART(year,AttendanceDate) = DATEPART(year,@Month_Beginning)

INSERT INTO AttendanceRoll
    (AttendanceDate, ContractID, PersonID,
    StartTime,
    EndTime,
    Hours, AbsenceReason,
    UpdateCount, SplitShiftID, ModifiedBy, ModifiedDate)
SELECT
    @P33,  @P34,  @P35,
    CONVERT(datetime,REPLACE( @P36, '.', ':')),
    CONVERT(datetime,REPLACE( @P37, '.', ':')),
    @P38,  @P39,
    @P40, 1,  @P41, GETDATE()

for (;;) {
    try {
        using (var t = BeginTransaction()) {
            DoTheCall();
            t.Commit();
            return;
        }
    }
    catch (SqlException ex) {
        if (ex.Number != 1205 && ex.Number != 601 && ex.Number != 605)
            throw;
    }
}