You could do either.  Tubal ligation reversal has a success rate of somewhere in the ballpark of 75%, but requires surgery.  IVF has as much as a 70% success rate, but keep in mind that it requires hormone injections, egg harvesting, and the risk of failure (which means you'd have to start over again, with the same expenses).

So, I guess you should probably talk things over with your physician and decide which is right for you, your pocketbook, and your patience.