The Wales Under-21 international made nine starts and two appearances in the league, scoring once.
Manager Mark Yates told the Robins' official website: "I'd like to thank Jake for everything and the effort he has put in since being here.
"We have to prioritise because we want to bring in other players including a striker."
The 21-year-old, who is yet to make a start for the Royals' first team, spent the majority of last season on loan at Exeter after a short stay at Aldershot.
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