You know how toddlers always start off with the 3 wants 'learn to walk/talk/potty train'? You can only lock one of them, and they take so long learning they've re-rolled and lost them by the time they've nearly achieved the skills. Is there a way to regenerate those specific wants? I've tried re-rolling with batbox but they never come back up. Often (in my game anyway) the toddlers only have 3 of their want boxes occupied and the fourth is merely a blank space by the time they're ready to age up, even with one or more of those 'high value' skills not yet learnt. It bothers me a lot! Is there some solution to force them please?

If they're stuck with just the three skilling wants and a blank, they just glitch like that occasionally right after you age them up from baby. Reroll their wants a few times and wait a bit and it should fix itself. If they keep rolling wants for snuggles/tickles/etc. instead of the toddler skill wants, just satisfy wants until they roll the toddler skill wants again. If they're not rolling regular toddler wants by the time they are ready to age up, you probably have a mod issue.

Not being able to satisfy skilling wants in time happens at all ages if you play a relaxed pace. Like how you want to get a badge in X, and it takes way longer to get than the lifetime of the want. Normally toddlers have enough simple wants like play with family member to boost their aspiration equally. If the wants don't come for you, it might be because of some cheats. People need a history with invisible root wants for others to come, which I haven't fully figured out yet. If you artifically switch ages with a debug object, then they don't get those root wants.

You can use cheats to add want locks, like after University, but of course those are not fair.

There is no way I know of that you can make a want to come back like that.

You can add locks with the Sim Blender and lock all them until you get them filled if you want to.
https://simfileshare.net/folder/92516/

If you don't mind "cheating", adding extra locks is quite handy, and is my preferred method for this. Personally I use the Insimenator mod (the aspiration adjuster item), but pretty sure the SimBlender or SimManipulator also have the option.

You can to some degree "train" sims to get the wants you want, in that they get back on the track for a want tree they've started on or wants ("milestones") within an age they haven't finished. If they have unfulfilled expected wants, they sometimes tend to pop back up again, but sometimes just need to be triggered by either time or actions related to the want (toddler wants, college wants, romantic wants, wants for gaining skill points, etc.). Some reroll automatically at an early time of the day, while others need to be triggered (skill wants may need you to let the sim gain a point, then reroll the wants, then they get the want, and it continues counting up).

Toddlers will sometimes reroll toddler wants on day 2 or 3.

Thanks everyone! It seems like sneaking on those extra locks is the way to go! I didn't know that was a thing, despite having the manipulator etc, so that's really good to know! I wouldn't want the adults to have locks they haven't earned, but for this one issue with the toddlers it seems like a fab solution! Thanks team! :-D

I find just filling the wants they do have a good number of times, will make at least one of those training wants come back.

Don't forget the Aspiration rewards Smart Milk (for the toddler) and Thinking Cap (for the teaching parent) make very quick work of the toddler skills. They can give you time for your tots to either re-roll, or for you to let them focus on other skills.