Can I buy Travel Insurance against the cancelation of a Formula 1 race?

From the Terms & Conditions of the Sinagpore GP

2.3.2. SGPPL will refund the cost of a Ticket to the Ticket Purchaser of that Ticket only if:

• the entire Race is cancelled and cannot be rescheduled;

• the dates of the Race are changed after they have been confirmed by FIA and the relevant Ticket Purchaser has confirmed in writing to SGPPL that he does not wish to attend the Race on the rescheduled dates;

• there is a significant change to the Ticket Holder’s reserved seating arrangements (other than as described in Clause 2.2.2 and as determined by SGPPL in its sole and absolute discretion) . If SGPPL makes any significant changes to the Ticket Holder's reserved seating arrangements, SGPPL will notify the Ticket Purchaser directly of such changes, using the contact details provided by the Ticket Purchaser at the time of purchase of the Ticket(s). SGPPL will offer the Ticket Purchaser the opportunity to ex change his Ticket for a Ticket of the same or lower face value to another reserved seating or general admission area. If the exchange is not acceptable to the Ticket Purchaser, SGPPL will refund the cost of that Ticket

So what you need is a normal cancellation insurance. If something happens and the race get cancelled or the date changes, they will refund the tickets. But to be honest - it's very very unlike that something happens and if the insurance costs more than 10% of the ticket price I would never make it. Bahrain 2011 was an exception and you don't have to worry that this can happen in Singapore