Another Jam won't set question

[Compact]

Sorry, have read a few here and think I've got the idea, want to check the recipe.

2.3kg of Raspberries
1.15kg of Jam Sugar (with Pectin). (some recipes say 1:1 ratio i.e. 2.3kg of sugar, but went with this one)
2 Lemons Squeezed.

The mixture was quite watery.

Boiled then simmered in total for 40 mins.
Doing the plate test.

In the end bottled (jar'd) last night and still not set this morning, nice and runny.

What should I do.

1. Wait another 24hrs
2. Reboil as it
3. Reboil with more sugar to get a 1:1 ratio
4. Reboil with more sugar and more lemon juice

Thanks in advance

Other questions

1. when putting in jars, is plastic or wax paper needed or just fill to the top(ish) and put lid on (washed and oven dryed)
2. If you can't fill a jar, i.e. 1 inch of space at the top, is there more chance it will spoil/mold?

Thanks

That's nowhere near enough sugar in my experience. It'll never set no matter how long you boil it. I'd go with option 3, reboil with more sugar.

On your other questions, plastic film and/or wax paper are not necessary as long as both your jar and jam are truly hot and the lid is sealed on immediately after potting. If I'm making a very large batch which I'll need to store for a long time, or am giving jars to friends, I'll put both a wax disc and a film circle on as well as the lid just as an extra precaution, but I don't bother when doing it for our own family. Although I'll also triple seal if my lids are in less than perfect nick, just to stop the jam coming into contact with the lid and causing any further deterioration in either the lid or the jam.

If I can't fill a jar and there's more than about half an inch space, I store that one in the fridge and make sure it is used first.

I've never had spoilage or mould on homemade jams when following these routines.

I always use a 1:1 ratio.
I you need to add more sugar to make up to this ratio and reboil it. you shouldn't need more lemon juice.

Don't simmer it. It needs to go up to 104 centigrade so it needs to be a really hot rolling boil. If you can borrow a jam thermometer off someone, so much the better.
Use the biggest pan you can as it will bubble up a lot, and you shouldn't be turning it down to stop it overflowing. If you haven't got a big enough pan try splitting it into two batches.

I'm not as conscientious as SparklingMuppet with sealing my jars, however I do check to make sure the lids are completely sound. Before filling them I wash the jars and lids, then microwave the empty jars for 3 minutes immediately before filling them. The lids are just washed and dried with a clean teatowel. Then the hot jam goes into a hot sterilised jar and the lid goes on immediately. The jam does not come into contact with the lid. It's a bit slapdash, and not the recommended method but I've never had a problem with spoilage, and I do make loads of jam.

I always wash and sterilise a small jar for the last bit of jam in the pan, which invariably won't fill a regular sized jar, and if the last bit of jam doesn't completely fill the jar, it gets used first.