Jaaskelainen joined Crewe in August 2017 on a one-year-deal after being released by Bolton Wanderers the previous season.
The 19-year-old son of former Bolton legend Jussi Jaaskelainen, Will has yet to make his senior bow.
However, he has impressed during short-term loan spells with Evo-Stik League South side Loughborough Dynamo and Evo-Stik League Premier outfits Nantwich Town and Buxton this season.