Look closely at similar homes to yours that have sold in the past 6 months, within a radius of just a few miles. Personaly, I would not mess with a so-called allowance. I would price it right the first time. Ask your agent......
The answer will be specific to your neighborhood and property, so it will be difficult for anyone here to give you a useful response without having more details about your property.
If the problem is "dated kitchen," you might be able to address it fairly cheaply. You don't want to put in a new $50,000 kitchen right before you sell; you'd never get that money back. However, you might put in $2-5k for superficial changes that might make a big difference.
For instance, instead of replacing the cabinets, you can replace the cabinet *fixtures*, which makes them look new. You can cheaply remove flowery wallpaper, repaint, or replace one or two old appliances (even with used ones, as long as they're better than what you have).
If there is a lot of general work to be done, or there are substantive functional or mechanical problems, I'd advise simply dropping the price to account for it. You can support this by doing a pre-inspection and providing the buyers with documentation of what needs to be done, with cost estimates. (They should always do their own inspections, of course.)
Note that I'm in PA and you're in Texas, so laws and guidelines could be different there. Consult a local agent for final advice.
Hope this helps!