Some claim that, if you leave eggs in the nest, a bird will go broody but that has never worked for me, no matter the breed. Time of year, age, breed, genetics,etc. can all play a part in whether a chicken goes broody or not, but I've never heard of someone being able to force a chicken to brood, nor encourage one with any level of success.
If you have a breed or genetics of a breed that are not known for broodiness, then obtaining a breed that is known for it and using her during those times of year that she goes broody may be an option.
OK, go outside of your comfort zone and add a couple of hens from breeds that are known to go broody, get two to make sure that you get one who will do the work. Silkies and many breeds of bantams can go broody at the drop of a hat. Buckeyes (whose breeding program seemed to be finished with a cross to gamefowl) are reputed to tend to go broody. Of course, if you get chicks or pullets, you will have to wait for next season. If you can't wait, then getting an incubator may be necessary.
(As Bee posted) It is not the time of year for many a hen to go broody. (Yes, you can get the odd one out... but do you want to ... at this time of the year.) But I'm not sure where you are at... So I guess I would say in my area... I would not want a hen to go broody now. lol
If you have "game chickens" ... then you need to look to no other for the best momma you can find.
You may need to look more at your housing/feed and water.