Hey there! I haven't tried Elise in the new jungle yet, but from what I've seen she's holding pretty steady. Her spiderlings, if used properly, tank jungle creeps and monsters for you, so you take less damage during your clears. I wouldn't go so far as to say she can get a leashless blue at level 1 like she used to, but she's certainly not super weak, and in fact during season 4 she had some of the fastest jungle clearing. Quite a few times I actually outpaced my normal rhythm and found myself having to wait several seconds for camps to respawn.
As for building her, you have two options with Elise: Tank with a solid bit of damage, or full on assassin.
For her tank build, you're focusing on a bit of early spell penetration with Sorc Boots, a Haunting Guise, a Rylai's Crystal Scepter, and finishing the Liandry's Torment, after which you just build straight tank. If your team needs even more tank than that, drop the Rylai's for another item with a bit more tank to it. Elise scales really well off of spell penetration because of her high base damages, so AP scaling isn't that high of a priority for her. As for the jungle item, if this were season four I would suggest Spirit of the Ancient Golem. The knee-jerk reaction in the current jungle would be to say use the Juggernaut enchantment, but given that it's pretty weak right now and not very cost efficient compared to the other items, I'd recommend using the Magus enchantment. She still makes good use of the 80 AP, and greatly enjoys CDR.
If you want her to be an all out assassin, dump into AP and spell pen/MR reduction. Magus enchant, Sorc Boots, Liandry's Torment, Rylai's Crystal Scepter, Rabadon's Deathcap, Voidstaff/Abyssal Scepter. You'll be dealing massive on hit damage in your spider form, and your Q will deal greatly increased percent health damage on targets, while your human form W will eat waves and champions alike.
Personally, I prefer her played as the former. Sure she can make for a great assassin given the potential damage in her kit, but even playing her as a tank I still find myself using her as an assassin all the same. Her ability to lock down single targets, especially after a Rylai's is finished, is simply amazing. She has more than enough damage on her spider form W to fight extended engagements against single targets after a human form E Q W combo while you get them weak enough to finish off with her spider form's Q. Learn to land her human form E, because landing that will make or break you as an Elise, and start practicing your spider form E so it's natural to use getting into and out of fights.
And remember: only the spider is safe in her web.