The question isn't clear. Are you talking about sample rate conversion of existing samples (interpolation filter) or increasing the ADC sample rate? In the latter case, you have to ask for the ADC hardware specification in a first place.
P.S.: I didn't yet notice post #5. According to it, it's a rate conversion problem. The first suggestion of simply repeating samples won't remove the image frequencies completely. For optimal performance, you need an interpolation filter. A CIC interpolator is the most simple method to do it.