I have recorded my data at X samples per second in LabChart 8. Is it possible to show the data at different sampling rates without re-recording the data?

This is an advanced solution.
It is possible to imitate the effect of resampling in LabChart 8 by using the in-built Arithmetic functionality.
To downsample:
Resample(ChX,Y,
Z) (with Z being optional)
Where:
X is the Channel Number containing the raw recorded data
Y is the factor you wish to downsample by. For example, if the Raw Data was recorded at 1000/s, setting Y to 4 would downsample by a factor of 4 (1000/4) giving you a Sampling Rate of 250/s (see attached example file).
Z can be used to interpolate, allowing you to upsample by a factor after downsampling. This is useful for showing sampling rates that don't divide into your sampling rate exactly - for example at 1000/s, if I wanted to show the signal at 300/s, I can use the formula Resample(Ch1,1000,300) - Y at 1000 downsamples the 1000/s Sampling Rate to 1/s, then upsamples by a factor of 300 (1*300), giving me a Sampling Rate of 300/s.
To upsample
Use the same formula:
Resample(ChX,Y,Z)
But with Y always being 1 (thereby not downsampling at all) and Z being used to then upsample by a factor.
Downsampling is also available when Exporting LabChart Data to a text file (under the File | Export option).
Note: Downsampling is referred to as Decimation in the LabChart 8 help, and Upsampling is referred to as Interpolation.