Double-click the Ableton desktop icon to launch the program. Click one of the folder icons and navigate to the directory that contains the sample you want to lengthen. Drag and drop the sample into a slot on the first audio track.
Click the "Warp" button in the Sample Editor window, if it's not already selected. Deselect "Loop" if it's selected.
Click and hold the field underneath "Seg. BPM." Drag the BPM counter upward to lengthen the sample. Release the mouse when the sample is at the desired length.
Press and hold the "-" key to zoom out. Click the right-hand end marker, which looks like a left-pointing arrow, at the top of the sample waveform. Drag the end marker all the way to the end of the waveform.
Launch Ableton. Press "Tab" to switch to Arrangement View. Drop the sample that you want to lengthen onto the topmost audio track.
Click on the sample. Click "Warp" and "Loop" in the sample's window.
Hover the mouse over the rightmost edge of the sample in the audio track. The mouse cursor changes to a "]" icon. Click and drag to the right to lengthen the sample. Release the mouse button when it's at the desired length.
Right-click the sample. Click "Consolidate." Ableton rewrites the sample to the length that you set.