Current gear seems decent enough to me. I've got an older version of the same boots, been wearing those since 2009 and they've served me very well.
If you're thinking about a new back protector, consider Forcefield -- wife & I both wear those (we both have a Pro L2K Evo, and I also have a Blade) and they're awesome. She put hers to the test in a big way in 2015 (where she absolutely obliterated her old GSXR and shattered bones in her wrist), and the ER doctor was amazed she had no bruising or injury of any kind to her back.
I have Icon Field Armor for my legs that I wear underneath my jeans sometimes on the street. Can't say I'd recommend it unless they've made some changes however. The protection seems OK (haven't put it to the test), but the leg straps are comically too short. I don't even have huge calves and they were still nowhere near able to reach far enough to fasten properly -- I extended them with double-sided velcro strips. Forcefield has a couple options here (and I'm a fan of their other stuff), but I have no experience with it.
Helmet-wise....beware, this is probably going to get long.
First and foremost, find something that fits your head well. This is something I didn't realize how wrong I was doing it until I found a helmet that actually did fit well....I went from an HJC CL-14 to an Arai RX-7 Corsair and hooooooly shit what a difference. Try a bunch on, find some that fit the shape of your head well (no pressure points and it stays where you put it on your head), and start from there. I haven't been in quite a while, but the motorcycle show in Chicago was a good place to try a wider variety of stuff on in the past...our local dealers don't carry shit for helmets, and what they do is largely low-end. I have a pretty standard intermediate oval shaped head -- I've had an Arai Corsair, Shoei RF1100, Shoei RF1200, Bell Star, and Bell Race Star, all of which fit very well. Wife had a scorpion that was ok, but honestly kinda cheaply constructed. She's really liked her Shoei RF1200 and Nexx XR2. I know price isn't necessarily an indication of quality in all cases, but I find myself rarely looking at anything that costs under $500 these days, FWIW.
Comments on recent helmets we've ridden with...
The Bell Race Star is what I'm wearing on track these days, and I think very highly of it. It's above your max budget ($700ish), however their 3-layer EPS liner design (called Flex, very similar to their MIPS liner) is something I think is pretty awesome (it's what got me looking at Bell in the first place), and the viewport is noticeably tilted upward for better vision in a race-oriented tucked position. My Star fits exactly the same and is almost as light (Race Star is carbon fiber shell, Star is not), just doesn't have the race-oriented viewport or the MIPS liner system. They've introduced a new Star MIPS for 2018 that has the MIPS liner system as well, and is in your budget zone ($500ish). Ventilation in both is ridiculously good, probably the best of any helmet I've owned. I crashed pretty hard in my Race Star in July and it did its job perfectly. No concussion, no injury, etc. Yes I'm sponsored by Bell, which may make this seem a bit shill-ish, but I was attracted to Bell for the features and safety aspects, and was going to buy one anyway before I applied for support.
Shoei RF1200 is also around the $500 mark for solids, but graphics are damn near $600. I rode in an RF1100 for several years, then picked up a 1200 after those were introduced. Fit well, good ventilation, quite lightweight. They made a lot of improvements over the 1100 that I was pretty impressed with, most specifically weight and noise reduction. The wife had her monster crash in her RF1200, and walked off with no injury to her head and no concussion. Vision on track is good, I rode with an 1100 or 1200 on track from 2012-2016 with no complaints.
Wife really likes her Nexx XR2, it's lighter than the Shoei and the viewport is larger. Price is lower as well ($400ish, or $500ish for the carbon version). No crash test data here, though.
She'll probably have either another XR2 next year, or a Bell Race Star.
Let me know if you're in the neighborhood and want to look at any of this stuff...might even have something you could try on too if you happen to be the right size.
The lighter, the better. Also, something a bit more aerodynamic. Sounds odd, but I remember lifting my head just a little bit at full tuck on the track this year and the air flow instantly wanted to rip my helmet off. I don't have a whole lot of experience yet, but it just struck me that it seemed far too easy for that too happen. Something with a wide and clear view in the riding and tucked position. Current helmet has terrible visibility if your head is down and you're looking up/forward. Wind noise...