First, make sure that your credit card company has your most updated income, because you might be due for a limit increase anyway. Once that's squared away, it's fine to have them do a hard credit inquiry because you'll most likely get approved if your credit score is decent. The hard pull will only ding your score temporarily (as long as you're not also applying for multiple credit cards around the same time), and you should be able to recover in a few months--especially if you have that higher credit limit and you don't end up using a ton of it every month. Credit utilization ratio matters, too!