what you could do is go to www.flagpagetest.com.
typically, this test is used to help couples understand each other. (so you and your husband/bf/whatever should definatly take it!) but there is no reason why a kid couldnt take it and have the same kind of result. it is 12.50 for each code to do the test, but its AWESOME and worth the money.
my brother is kinda like this. hes slow, procrastinaty, all of that. the number one thing we have to do is stop labeling. especially negative labels like "lazy". thats not motivating. the flag page test has a list of adjectives. she would choose the ones that DEFINATLY describe her. not ones that maybe describe her, but DEFINATLY. very important thing to note: DO NOT HELP HER CHOOSE ADJECTIVES. you can help her if she doesnt know what one word means, but do not tell her she has to pick any. my brother literally picked 5.
and he ended up getting a profile that perfectly describes himself. the reason he seems like hes slow and lazy is because he only wants to do things the easiest and most perfect way that he can. this isnt a form of laziness; its a method of how he feels in life, and he likes that about himself. connect this to the next idea i mention.... : giving her the tools to make it easier and perfect for her to clean her room.
she cries because her room is so messy? this sounds more like a problem of her not knowing where to start, and really not having the tools to actually clean her room or keep it more tidy, than her not wanting to or just not choosing to clean her room. perhaps take a trip to a store and get her some baskets, shelves, whatever, so she has a place to put things. let her pick things out that she is excited about. (remember to make a budget though beforehand and try to stick to it - then it also becomes a budget lesson :P)
get her hooks to hang things on. does she like to fold her clothes and put them in a dresser? or would she prefer to hang most of what she can? im a hanger, so i have all my shirts hanging, and i bought a hanging shoe organizer (one with shelves, not slots) and i put my pants into the little shelves. you can but the bigger ones as well if you prefer. find a way to figure out how she would like to organize her room, and give her the tools to be able to do that.
does she have too many things in her room to begin with? perhaps she and you can look through her things and donate them to a needy kid in the neighborhood, a friend, whatever. also; dont forget the power of bartering; get her friends together, or kids of similar sizes, and have a huge clothing swap. for every item a kid brings, they get to bring home a similar item. it doesnt matter how many things a kid brings, everyone should swap something. any extras can be donated to a goodwill or something. find something that will get her excited about downsizing (better now than after shes had her own place for 20 years and stockpiled a bunch of "things" that dont even matter or get used!)
anyway, this doesnt sound at all like shes lazy, it sounds like shes overwhelmed. help her by giving her a list. instead of "clean your room" you break it down; "first pick up dirty clothes and put them in the hamper/laundry. second pick up clean clothes and put them away _____. third pick up books and put them ____. fourth pick up puzzles.... fifth pick up ____ kind of toys, etc. break it down so that she has an eaiser time staying on track. if us moms make lists, why shouldnt kids need them too? when i am going to clean the house, i definatly need a list. when im going grocery shopping, i definatly need a list.
anyway, try to work with her to figure out how to help her . and try to find more positive traits (the flag page test will do that!)