At the moment Inter's condition is different from when he was before.
He could shine that time because Conte was able to maximize his ability well but now the era of Inzaghi and Lukaku is very difficult with this.
I think it will still be difficult for him now because regardless of what if his performance is not as good as the first time he was at Inter then indeed Inter will also be reluctant to keep Lukaku.
After from Inter to Chelsea Lukaku's performance declined and it made the Chelsea management decision to loan him to Inter Milan for one season, but after he was at Inter Milan his performance had not recovered but after he was injured it worsened his situation until now, and even now there is news about Lukaku being ready to be loaned again to Inter Milan for another season before Chelsea will sell him later despite saying they lost millions of dollars.
It looks like Chelsea don't want him to return to Stamford Bridge considering that there is already Aubameyang who is even more relevant than Lukaku, it is said in the Mirror article Inter will be ready with this agreement.
https://www.mirror.co.uk/sport/chelsea-ready-write-millions-selling-28286850It’s been a tough year for Romelu Lukaku, there has been a lot going with him, from falling out of favour with Thomas Tuchel to having a poor form and then dropping off the first eleven and getting shipped out on a season long loan and getting injured at arrival. I feel pity for him at this moment. Inter Milan has now ruled out a possibility of terminating his loan contract and wants to keep him until the end of the season.