I would just go ahead an replace it anyways. I should recommend the Stealth Brand Heaters. Firstly, if you order them online, they aren't that pricey. Second, they aren't made of glass so you don't have to worry about it cracking, and lastly, they have an auto-shutoff switch to where they will turn themselves off if taken out of water.
I use them in all my tanks and have never had a problem with them. There are other good brands, of course, but this is just the best in my opinion.