[Remy]

I made a lot of pumpkin marmalade but ran out of jars. Would it be ok to warm up the marmalade again when I get more jars?

[madcat]

Yes - just till it gets to runny pouring stage and it will be fine.  You might need to be a bit more careful sterilising your jars, as you cant use the heat of the sugar to kill any last bugs. 

[mumofstig]

I always bring it back up to boiling point and then pot it.

I do the same thing if I need to change jars or lids for any reason. (sometimes I like to use pretty jars for presents, so need to repot )