I signed a player without work permit, and it's stated for the next application of the permit I'd have to wait for 120 days more. Now his loan has finished and 120 days have passed but I don't see the option to apply for a permit on the pop-up menu? Can I reapply for it or does he have to mandatorily get EU nationality in order to play for me at this stage?
Getting a work permit can be tough but you can do a few things to stack the odds in your favor.
Make sure the footballer you are trying to get the work permit for is a first team member of a nation ranked in the top 70 for at least three consecutive months, including the month you are attempting to get the permit. The more highly ranked the team the better your chances. This also applies for the youth teams.
If you can't re-apply for him probably is due to this rule.