The result has seen Spain stay three points clear of second-placed Italy, who recorded a 1-0 win at home to Israel, with just two fixtures left to play in the section.
Isco almost doubled Spain's lead in the sixth minute after looking to pick out the top corner with a curling effort, but Jehle was across to make a smart save as Liechtenstein continued to come under intense pressure in the early exchanges.
Spain had more than 80% of the possession inside the opening 12 minutes, with an attack versus defence exercise seeing Lopetegui's side continue to move the ball in the final third of the field.
La Roja had their second of the match in the 15th minute when Morata headed an Andres Iniesta cross into the back of the net, and it became 3-0 less than one minute later when a mis-kick from Jehle presented the ball straight to Morata, who squared for Isco to find the back of the net with ease.
Morata headed an Iniesta cross past Jehle for the second time in the 26th minute, but the offside flag denied the Chelsea forward, even though replays clearly showed that the 24-year-old was level. Morata was then denied by the diving Jehle as Spain continued to cut through Liechtenstein at every available chance.
Spain made it 4-0 in the 39th minute when Silva picked out the top corner with a brilliant free kick, but Liechtenstein almost stunned the visitors moments later following a mistake from David de Gea, only for the Manchester United goalkeeper to produce a routine save from Michele Polverino's effort.
Aspas then turned provider three minutes later as the Celta Vigo forward set up Morata, who carefully slotted into the bottom corner for his second goal of the night.
Jehle made a smart save to keep out a Morata header just before the hour, before denying Gerard Deulofeu moments later as the score stayed at six entering the final 30 minutes of football.
Aspas helped himself to his second of the night in the 63rd minute, however, as he smashed home from close range.
Monreal should have made it 8-0 Spain in the 72nd minute after meeting another brilliant free kick from Iniesta, but the Arsenal defender somehow headed over the crossbar from close range.
Iniesta was next to come close for the visitors in the 85th minute, but the Barcelona midfielder just missed the crossbar with a long-range attempt. Spain did make it 8-0 in the 89th minute, however, when a low Deulofeu cross was turned into his own net by Maximilian Goppel.
Next up for La Roja is a home game against Albania on October 6, while Liechtenstein will host Israel on the same night.