Why replace the existing garage door when you can fix the damages? The question is: are problems with the panel repairable? What are the usual problems? Some are under the impression that a few dents won't make a difference to the way the door moves and it really doesn't. Though, such problems are not immediately associated with the overall operation of the system. The problem is that the dent will expand, the top coats that protect the material from elements will be scratched and eventually the door will rot, become weak and unable to offer you the right protection.
Naturally, the best way to deal with similar problems is to take care of them right away. For example, dents must be scrubbed immediately and repainted. Otherwise, they will become bigger and soon you will find rust. When garage doors corrode, they will become weak and won't provide the necessary protection. Of course, the most difficult thing is to treat wood doors that have warped. Such problems are hardly repairable, gradually they will worsen and eventually the door won't close properly. In such circumstances, you will be required to proceed with garage door panel replacement and for this reason it's best to treat the door often to avoid such issues.
Problems related to frames, the bottom seal or the windows are surely fixable. The weather strips can be changed, the frames can be repaired and broken glass panels are definitely replaceable. Your door won't rot if you maintain it regularly. If you detect minor problems, scrubbing the surface or the damaged part with sand paper and repainting it as soon as possible is your best chance to avoid the door's replacement.
As an overall, taking care of issues at once is the secret of keeping the door in great condition for longer.
Don't forget that the door is usually dented when you bump the car into it, so you will know of the damage. Though, problems related with the passing of time or the effects of weather will be taken care of with frequent garage door maintenance. So, it's also prudent to prevent issues, too.